Alien Biospheres Part 12: Sociality & Cooperation Explained

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resources on all sorts of writing and world building topics to sign up for campfire or to learn more check out the link in the description [Music] last time we explored the effects of ecological isolation on the island dwelling clades across the planet but in the meantime the mainland clades will continue to diversify and develop new survival strategies involving not only physical adaptations but also behavioral ones one class of behaviors that deserve special consideration is cooperation which encompasses any behavior in which multiple organisms work together for each other's mutual benefit at first glance organisms cooperating with each other seems somewhat paradoxical an organism that behaves altruistically expending its own resources and energy to help another individual will have fewer resources for itself and is therefore inherently more likely to die and so won't spread its altruistic genes onto the next generation while a selfish individual will be able to acquire more resources for itself and will therefore be better able to survive and reproduce meaning that natural selection will always favor selfishness and yet cooperation both within and between species is extremely common in nature so there must be some circumstances under which organisms gain greater fitness from cooperating with others than they would from acting individually one of the more common examples of this occurs in mutualistic symbiosis contrary to its popular usage symbiosis refers to any long-term association between two species regardless of whether their relationship provides a benefit or a detriment to either one this means that parasitism is also considered a form of symbiosis as is commensalism when one species receives a benefit without any net gain or expense to the other while a situation in which both participants benefit is called mutualism so far in this series we've already seen several instances of mutualism such as between the early chemotrophs and their algal symbiotes and the co-evolution between the chromatophytes and the pycopterans mutualism will be selected for if the benefits conferred to both species outweigh any costs to either of them although the algal symbiotes need to provide their chemophyte host with a portion of the sugars they produce they gain the benefit of making sure the host they depend on stays alive and healthy and in the chromatophytes the cost of expending energy to produce nectar is outweighed by the reproductive benefit provided by the pollinators that the nectar attracts but these are only two examples among thousands that will emerge across the planet's history some species may resort to entering mutualistic relationships in response to the ever-changing climate as the ice age comes to an end the mountains that once separated the coastal rainforest from the rest of the eastern continent will erode allowing the species native to the rainforest to spread inland however many of the rainforest clades have specialized for lifelong arboreality never once coming down to the forest floor a lifestyle that's only possible because of the density of the rainforest canopy but although the erosion of the mountains will allow the rains to reach further into the continental interior the inland forests won't grow anywhere near as dense as they do along the coast and in most areas groves of trees will be separated by large stretches of open landscape that would be very difficult and dangerous for arboreal animals to cross by themselves so they'll be confined to relatively small patches of territory with a suitable density of trees to disperse to new areas they may have to rely on the assistance of other animals in part 10 we briefly brought up phoresis using another organism as a means of transport phoresis is considered a form of commensalism since the phoretic species gains the benefit of increased dispersal without any positive or negative consequence for the host pharesis will be an optimal solution for animals like the pronocathetes and the other dollar caustracans as while almost none of the terrestrial loafer storms are very mobile the arboreal dolo costa cans are especially cumbersome on the ground because their limbs have specialized for crawling along branches phoresis will provide a means of dispersal for at least one clade of pronachanthids who may climb onto the backs of passing herbivores to be ferried across the steppe and scrubland to reach new patches of forest not all herbivores are likely to tolerate a 20 centimeter pronocanthod clinging to their back but the presence of the pronocanthods does provide them with some advantages for one thing the pronocantes will feed on the malacca forms that infest their hosts hide ridding it have parasites in a similar way to cleaner fish and oxpecker birds but the pronocanthids also offer the herbivore an extra degree of defense the pronocathet's fringe of venomous spines whose dangerousness is advertised by their vibrant apostomatic coloration will be enough to deter most predators perhaps one clade of leptopods evolves to seek out and accommodate the pronocathes to protect itself like a living suit of armor and once this relationship evolves co-evolution will ensue with both clades specializing to make the relationship as efficient as possible because the pronocanthods are now their primary means of defense the leptopods won't need to invest much energy and speed so they can afford to become more heavily built with broad backs to provide space for as many pronocantes as possible and as the pronacanthas become increasingly reliant on the leptopods they may specialize for phoresis by turning their limbs into pincer-like appendages to secure themselves to their host much like how remoras have adapted their dorsal fin into an adjustable suction pad to attach themselves to larger fish we'll call these pronachanthids phylactocanthids and their leptopod hosts hoplopods but as this instance of cooperation evolves another will need to occur simultaneously the greater the number of phalactic methods on the hoplopods back the greater the collective defense they can provide meaning they'll have to cooperate not just with their hosts but also with each other sociality is the degree to which individuals of the same species or con specifics tend to associate with each other unlike mutualism sociality comes with an unavoidable cost if the organisms are members of the same species they'll be competing for the same resources which discourages cooperation so the vast majority of species are solitary for sociality to evolve there needs to be some benefit that outweighs the costs of this intraspecific competition and results in a net gain for every individual involved in the social interaction one such benefit that frequently drives the evolution of sociality is mutual protection from predators since having more individuals around makes it easier to keep an eye out for danger and presents a more formidable barrier against attackers this will be the case for the phylite decanthats as well as for the captopods alibrackids and the many other herbivores across the planet that have evolved herding behaviors in most of these species these social groups will have a very loose structure and the animals that comprise them will simply tolerate each other's presence without forming any lasting social bombs consequently these social groups will be fish and fusion societies fluctuating in size and composition as new members come and go but other animals may evolve to form more long-term associations with each other although the lattopterns originally evolved in forests some species may eventually spread into open habitats like the steppe and scrubland but whereas in forests they can find food in the canopy far out of reach of the predators on the forest floor in the step they'll have to descend to the ground to forage for malacca forms and other small prey among the brachiophytes where they'll be much more exposed and vulnerable because of this many species may gather in groups while foraging increasing their collective vigilance and as they become increasingly reliant on the other group members for protection they may more efficiently coordinate their activities by evolving a division of labor sentinel behavior occurs when an individual forgoes foraging for food to assume lookout duty alerting the rest of the group if they spot danger seen in a wide variety of social animals like barbary ground squirrels prairie dogs and pied babblers sentinel behavior is a prototypical example of altruism since the sentinel not only misses out on feeding opportunities but their alarm calls may also attract the predator's attention making the sentinel a more likely target this once again raises the issue of how this behavior can persist we'd expect the individuals that exhibit sentinel behavior to eventually die out and their altruistic genes along with them but acting as a sentinel may ultimately be worth the trouble if the other group members can return the favor reciprocal altruism occurs when an organism behaves altruistically towards another individual with the expectation that that same individual will later carry out the same behavior for it in return for example vampire bats regurgitate a portion of the blood they've drank to members of the roofs that have been less successful in their feeding and are in turn fed by other bats when they've been unable to find food reciprocal altruism can serve as a way for sentinel behavior to evolve all the individuals in the group will take turns as sentinel mindful of the payback they receive when others take their turn but this raises another problem what's to stop one individual from simply never taking a turn as sentinel receiving the benefit of the other group members altruism without ever going to the trouble of reciprocating it this risk of exploitation poses a danger to the entire group so they'll have to ensure that every member of the group pulls their weight punishing or even exiling individuals that try to cheat the system this requires the cognitive capacity to recognize each of the group members and to keep track of who's been serving their time as sentinel which will be easier to do with fewer individuals in the group so unlike the more or less random congregations of the cantopods and alabrachias these latopterons will live in small tightly knit groups with a low degree of fission fusion dynamics and strong social bonds between group members however this whole system relies on the sentinel having some way of alerting the other group members to danger so these lotopterans will need some way of producing alarm calls animals on earth show a huge variety of different mechanisms for creating sound some like stoneflies simply tap their legs or abdomen against the ground while cicadas produced their characteristic sound using corrugated drum-like structures in their abdomen called timbals and others like the death's head hawk moth and the madagascan hissing cockroach create sounds by rapidly expelling air from their mouth parts or spiracles but one of the most common forms of sound production is stridulation where a sound is produced by rubbing or scraping two body parts against each other for these la topterans one of the very few parts of their body they can feasibly use to produce sounds is their teeth initially they may signal to each other by flexing their oral tentacles to scrape or rattle their teeth together and as they become increasingly dependent on these sounds to communicate danger some of these teeth may lose their role in feeding and evolve into specialized stridulating structures with which they can produce a range of chirping sounds [Music] however these calls will be of little use if they have no way of being detected hearing is extremely widespread though not universal in animals on earth while all tetrapods have inherited a similar hearing structure from early fish hearing organs have independently evolved over two dozen times among arthropods with their placement being extremely variable between clades but almost all of these hearing organs have converged on a similar structure consisting of a membrane called a tympanum or eardrum which vibrates in response to nearby sounds stretched over a hollow chamber through which the auditory nerves run most loafer stones have a fairly unspecialized hearing mechanism simply detecting vibrations that reach the sensory nerves within their oral tentacles and eyestalks but in species that communicate using sound as these latopterons do the hearing organs tend to be especially sensitive to the frequencies of the sounds they produce which may require more acute hearing so the areas of the nervous system that detect and process vibrations may enlarge into dedicated auditory lobes with the nerves running into hollow chambers on either side of the eye stalks with these physical adaptations maximizing the efficiency of their group behaviors these small letterings which we'll call pipiodonts will be specialized for sociality living in cohesive groups of five to ten individuals with a sentinel perched at all times on a nearby tree or other elevated position to make it easier to scan their surroundings but beyond group defense sociality can also provide a benefit to predators pack hunting is a behavior in which multiple individuals work together to bring down prey seen in a disparate variety of clades like wolves lions hyenas and even invertebrates like velvet worms but despite it having evolved so many times pack hunting has only been observed in less than 10 of carnivorous species suggesting that in most cases pack hunting isn't an evolutionarily stable strategy the primary benefit of pack hunting is that it allows a group to take down prey too large or well defended to tackle individually but the drawback is that every kill will have to be divided among everyone in the pack meaning a smaller share of food for each of them if the average prey is small and common enough to be taken down by a solitary predator or doesn't provide enough food for more than one individual then pack hunting won't be an effective adaptation this may be why on earth pack hunting is extremely rare in rain forests and other regions with abundant prey and is found almost exclusively in tropical step as well as occasionally in temperate plains and tundra all habitats where widely dispersed populations of large prey force predators to work together the tropical plains of the western continent are home to the titanopods many of which are too large for even apex predators like the incidents to feasibly take down on their own which may prompt some species to form packs the size and structure of which will depend on several ecological factors a larger pack will let them take down bigger prey but not only will it mean a smaller portion of the kill for each pack member but also just like in reciprocal altruism a larger pack will be more susceptible to cheaters as only so many pack members will be needed for a successful hunt and any superfluous members that don't participate in hunts will still benefit from the other pack members efforts the optimal group size will therefore be equal to the minimum number of individuals required to take down their typical prey which for these incidents may be somewhere between four to ten pack members in some pack hunting species group size and cohesion fluctuates with the availability of prey foosa are mostly solitary but they have been observed occasionally grouping up to hunt together which may be a lingering remnant of older pack hunting behaviors that evolved to help them hunt the now extinct madagascan megafauna but species that specialize for pack hunting may evolve more permanent associations and more sophisticated behaviors such as a division of labor among the pack members each individual filling a different essential role during the hunt when lionesses stalk their prey some pack members take the role of wings encircling the prey and driving it towards the centers who wait an ambush while chimpanzees divide hunting duties into up to four highly specialized roles the need for different roles to be filled during the hunt can even lead to cooperative hunting between different species such as how groupers are known to cooperate with moire eels which are able to slither among stands of coral to flush prey into the open where the groupers can more easily catch it increasing hunting efficiency for both species like many pack hunting animals these enzodons may establish hunting roles based on age size and experience with the younger pack members surrounding the prey and blocking its escape while the older and larger members move in for the kill these tactics will give these enzodonts which we'll call prionodonts a competitive advantage over their solitary relatives and let them tackle large prey that most other predators would struggle with as well as increased protection and hunting success another big advantage provided by sociality is easier access to reproduction after all even if an animal remains solitary for its entire life as long as it reproduces sexually it will still need to cooperate with another individual to reproduce which can drive animals to congregate to make fining mates easier one common example of this is lecking a mating behavior in which the males of a species gather in a single location during the breeding season to compete in courtship displays and attract visiting females these gatherings or lex make the process of mate selection much more efficient since the females won't need to waste any time or energy searching for a match when all the males are gathered in one spot and it will be easier to judge the males against each other and evaluate who will be the best mate because all the males carry out their displays in such close proximity to each other lex inherently involve a high degree of male competition which relating to what we covered in part 10 often drives the evolution of male display structures and ornamentation that they can use to compete with each other and as such lacking is strongly correlated with sexual dimorphism this being the case lacking behaviors may evolve in sexually dimorphic clades like the serrata brackets and karitha brackets who will gather in huge groups during the mating season all across the landscape of the western continent in most lekking species lex occur within a single relatively small area with the males within sight of each other but if some species live in areas of dense vegetation or other environments with a limited line of sight then the males can't rely on visual signaling alone to attract females and so may evolve to advertise their position using sound while stritulation is a very widespread method of sound production for animals with active respiration like tetrapods and osteopods the movement of air through the respiratory tract provides an easy way of generating calls which when produced in this way are called vocalizations many vertebrates have evolved special organs to augment and amplify their vocalizations like the syrinx and birds and the vocal cords and mammals osteopods have two separate breathing canals one on either side of the body most species don't have any well-developed means of creating vocalizations though some may be capable of forcefully exhaling to produce grunts chirps or whistles but as these karitha brackets increasingly rely on these vocalizations to attract mates their airways and spiracles may evolve special resonating chambers to let them produce bellowing or trumpeting calls [Music] again however these vocalizations rely on these karithabrak as being able to hear one another the ancestral osteoporosis hearing mechanism developed from the mechanoreceptors that let them detect vibrations underwater which in the transition to life on land evolved to become sensitive to specific frequencies functioning in a similar way to the sensory hairs of some insects and the hair cells inside the inner ears of vertebrates the majority of the acetate will be concentrated on the pedops so they can be angled towards a source of noise in much the same way that many mammals can adjust the position of their ears while some early clades may maintain this simple design many later forms will evolve more acute hearing by developing tympanic hearing chambers within their pedophiles which will be inherited by most of the subsequent osteoporotic clades since these karitha brackets rely on long-distance auditory signals to coordinate their social activities their hearing chambers may enlarge and become more sensitive to lower frequencies to let them discern each other's calls these animals which we'll call camara brackets will remain in relatively small fish and fusion societies outside the breeding season but will form lex of up to a hundred males spread out over many square kilometers of variable or forested terrain relying on their vocalizations to stay in contact with each other because each male aims to attract as many females as possible lekking is usually considered a form of polygeny a mating system in which within a given breeding season a single male will mate with multiple females while a female typically only mates with one male polygeny is one of the most common types of mating systems seen in as many as 90 percent of all mammals which isn't too surprising considering that as described by bateman's principle males receive a greater reproductive benefit from multiple mates than females do but while in lecking species a male will typically form no long-term bond with any of the females he mates with if the females represent a limited resource then the male may need to protect his access to mates by forming permanent associations with them a harem is a form of polygenous social group usually consisting of a single male and multiple females all of whom stay together throughout the year and function as a cohesive group ensuring that the male always has access to mates haremic mating systems may emerge among some species of captopods many of which have already evolved basic herding behaviors so forming horums may help these species achieve a greater degree of reproductive success but evolving to live in the harems may also prompt some physiological adaptations because the harem represents the male's access to reproduction the dominant male will need to defend it from other males who try to mate with his females any males that are unable to acquire or maintain their own harem may engage in kleptogrammy or sneak mating infiltrating another horum while the dominant male is distracted and mating with some of the females or they may even challenge the dominant male directly for control of the harem this means that competition between males is often very high in haremic species which once again drives the evolution of sexual dimorphism in these captopods the males may become larger and more heavily built than the females and evolve prominent horns and facial armor with which to spar with each other although these horns can serve as formidable weapons most of the time the males will seek to avoid injury and so will instead simply try to intimidate their rivals into backing down in animals on earth threat displays like these commonly involve vocalizations so the males of these captopods may evolve special membranes in their spiracles to help them produce deep booming growls to scare off opponents [Music] but unlike the harems of tetrapods on earth the males of these captopods will face an additional source of competition as a consequence of sequential hermaphroditism in sequentially hermaphroditic species the change from one sex to the other normally only occurs if it's likely to increase the individual's reproductive success which in the case of horums if a female were to become male then since the harem is formed almost entirely of females her number of potential mates would hugely increase therefore whereas monogamy and random mating systems are correlated with protandry protogeny is most often associated with polygenis and especially haremic mating systems so whereas most of the distantly related allo brackets on the western continent will be protandrous these captopods will be primarily protogenous but while becoming male may ostensibly give a female more opportunities for mating it's unlikely that this will be tolerated by the harem's dominant male as he'll want to keep all the females of the harem to himself so he'll need to assert his dominance to maintain his position at the head of the group and discourage any of his females from challenging him if a female begins to perceive the dominant male as an unfit mate or an inadequate leader this may trigger her transition from female to male after which she'll fight with the dominant male and attempt to take his place with this social structure these captopods which we'll name svena seratons will have constant access to reproduction while benefiting from each other's mutual protection but although polygeny seems to maximize reproductive success for both sexes there are forms of social organization that are based around other mating systems in part 10 we discussed how monogamy evolved in the amphidonts in response to living in desolate environments at very low population densities conditions under which males gained a greater degree of reproductive success from a single mate than from many when they first evolve they'll be solitary and territorial but when the glacial cycles end the warming climate will increase the levels of rainfall across much of the continental interior turning some of the regions of cold desert and tundra where the amphidonts live into tracts of step and scrubland although these habitats will have a greater abundance of food they'll also support a greater diversity of prey and predators presenting the amphidonts with new sources of competition while their adaptability and relatively small size will be a great asset some amphidonts may further avoid competition with the larger daylight predators by evolving nocturnal or crepuscular lifestyles to help them hunt in low light and to judge distances more accurately their lateral pair of eyes may enlarge and evolve special bones that allow them to be swiveled in different directions to track prey which may also function as sclerotic rings to help the eyes maintain their shape to complement their keen vision they may also evolve more acute hearing but unlike the kamara brackets these forms will have the openings of their hearing organs positioned at the apex of the pedopalps so they can be more easily turned towards a source of noise and an ear canal running down to the tympanic membrane within these openings may be surrounded by tufts of hair that keep them clear of debris as well as to help funnel vibrations into the ear canal in a similar way to the pine and mammals this improved hearing will make it more feasible to communicate through vocalizations so they may evolve expanded respiratory tracts with special valves to let them produce a variety of rasping chattering growls but on top of these physical adaptations evolving sociality will also give them a huge advantage as even though their ancestors were fiercely territorial the increase in local resources as the climate changes will reduce interspecific competition and pack hunting may be the only feasible way to take down many of the large herbivores they now share their range with so they may evolve to live in clans consisting of anywhere from three to fifteen monogamous pairs like in all social groups conflicts will occasionally arise between clan members over access to food and mates to streamline these interactions many social animals form dominance hierarchies in which every group member has a social rank that represents their access to food and reproduction relative to the other group members in most species dominance is established by size age and aggression but it can also vary based on sex in african wild dogs males and females occupy two separate hierarchies and in hyenas even the lowest ranking females are still dominant over the males hyenas also determine dominance through nepotism with offspring inheriting the rank of their parents in the ancestral amphidonts the need to defend fixed territories resulted in the females evolving larger body sizes and more aggressive temperaments than the males which in these social species may translate into dominance hierarchies that naturally favor females with the proviso that since these animals are protandrous a male may end up becoming female if he stands to gain dominance in so doing sex may also play a role when it comes to dispersal to avoid inbreeding social animals will need to periodically evict individuals from the group to join or establish another in the majority of social species males are more likely to disperse than females especially in polygynous systems like horums where the young males are exiled from the group to live solitary lives until they form harms of their own occasionally joining up with other males in small groups called bachelor herds in contrast female dispersal is quite rare but most often occurs among monogamous species or those with low levels of mate competition and a need to defend their access to local resources so since these amphidonts retain the monogamy of their ancestors they may therefore favor female dispersal but sociality offers additional reproductive advantages than just increased access to mates one of the most common forms of altruism is parental care acting in a way that increases the chance of the organism's current offspring surviving by incurring a cost to its own survival and its potential to bear future offspring the factors that favor parental care are encapsulated by case election the general trend being that the greater investment a reproductive effort represents the greater the pressure will be to ensure that the investment pays off so species with slow growth rates or that require large amounts of resources to reach maturity will benefit the most from parental care but recall that reproduction is typically a greater investment for females than for males so females usually experience a greater selective pressure to ensure the young survive because of this the most common form of parental care is female only parental care seen in almost all mammal species while male only parental care is much rarer especially in animals with internal fertilization but if sexual selection is low and if there are any ecological factors that increase the cost of reproduction for the male as well such as if juveniles have very low survival rates then the male may be incentivized to incur the cost of losing out on additional mating opportunities to help the female and caring for the young resulting in biparental care biparental care often goes hand in hand with monogamy since investing in a single mate means the male can expend the energy he would have spent searching for more mates into caring for the young instead biparental care is seen in the vast majority of bird species possibly because they are highly altricial young require a great amount of care from both parents to survive although monogamy initially evolved among the solitary amphidonts as a response to low population densities it also provided the opportunity for the males to assist in parental care so biparental care will be an ancestral trait for the amphidonts but the species that evolve sociality will have the opportunity to employ an even more effective strategy there are other ways for an organism to pass on its genes than simply producing offspring in a species that reproduces sexually an individual inherits half of its genes from each of its parents and will therefore also share half its genes with its direct offspring statistically it will also share on average half of its genes with each of its four siblings a quarter with half siblings and eighth with first cousins and so on this means that when an individual reproduces it's not only propagating its own genes but also those of its relatives and thereby acting to increase their fitness as well as its own this concept is called inclusive fitness and provides a way for altruism to still result in a net reproductive benefit the conditions under which altruistic behaviors will be selected for are described by hamilton's rule which takes into account this proportion of shared genes or relatedness as well as the cost to the initiator of the altruistic act and the benefit to the recipient hamilton's rule predicts that the more closely related two individuals are the more likely they are to behave altruistically towards each other since the greater the proportion of their shared genes they're helping to propagate and the greater inclusive fitness they gain because of this most social species usually have a relatively high degree of relatedness between group members meaning they all gain inclusive fitness from one another's reproduction to maximize this benefit some social species especially monogamous ones exhibit cooperative breeding in which young receive care not only from their parents but also from other members of the social group usually called helpers in this context if the clans of these amphidonts have a suitably high degree of relatedness then they may seek to increase their inclusive fitness by sharing the duties of parental care among the entire clan all the clans young will be kept together in a communal nest site and the adults will take turns guarding them while the others are off hunting giving these amphidonts which we'll call xenopsids a very high rate of juvenile survival but if the right ecological factors are in place some clades may evolve to take cooperative breeding one step further one of the osteopod clades that's most reliant on parental care are the trepanocyrants as their highly altricial young or grubs are completely unable to fend for themselves until they develop bones and functioning eyes in the semel paris species the female can afford to expend all of her energy into caring for the young since she inevitably dies once they're developed enough to leave her protection but species that can't afford such extreme parental investment may rely on another form of cooperative breeding once again the higher the relatedness between the individuals the greater the inclusive fitness an organism will gain from helping a relative's offspring and so the stronger the impetus they'll be for cooperative breeding this being the case one of the most common types of cooperative breeding is the rather poorly termed helpers at the nest in which care is provided to an individual by its older siblings who remain with their parents instead of dispersing to begin their own broods if this happens in the tripana kyrids while the males may remain semalparas the females may evolve longer lifespans to let them produce many clutches of offspring over multiple breeding seasons similar parity operating asymmetrically between the sexes like this is fairly common in semi-paris species on earth and will provide these trypanic iris with the opportunity for each clutch the female produces to help care for the one that follows it remember though that relatedness is only 50 between four siblings so if a single female has multiple clutches of young with different males then the average relatedness between all of her offspring decreases along with the inclusive fitness they gain from helping each other so helpers at the nest will be most strongly selected for when the relatedness between siblings is maximized in other words that they all have the same father meaning that monogamy is an essential prerequisite for most forms of cooperative breeding however there are ways to ensure maximum relatedness without forming an exclusive pair bond in some animals the female has the ability to store the male's gametes within her body for an extended period after he inseminates her and to choose when to use them to fertilize her eggs and if the female is inseminated by multiple males she can even choose which male's gamete she uses in this way the female can produce multiple clutches of offspring over her lifetime from only a single mating and can guarantee that all of her offspring have the same father to make the relatedness between them as high as possible ensuring they gain the maximum possible benefit from cooperative breeding the helpers can also forage for food dig and maintain the burrow and engage in sentinel behavior to watch for predators to signal to each other these animals may once again evolve a means of producing vocalizations all urochirids have complex scent chambers within their spiracles inherited from their scavenging ancestors which in these creatures may develop specialized vibrating vocal folds to produce a variety of high-pitched chirps to pick up these calls they may evolve in large tympanic hearing chambers from the hollow space left behind as their pedophiles shrink into antennae with small bones at the base of the pedophiles helping to conduct vibrations like the middle ear bones of mammals fossorial animals tend to lack pine and other external structures that might otherwise make it difficult to squeeze through tight burrows so these hearing organs and the pedopalps they're attached to will remain relatively indistinct and since the pedopelps have entirely lost their role in handling food their mandibles may evolve into a multi-purpose beak-like structure equally equipped to handle both meat and plant matter for which we'll give them the name ramfordons in most cases these ramfordance offspring will remain with the mother and maintain their role as helpers for at least one full breeding season eventually dispersing to begin their own broods but if helping their mother reproduce returns an especially high degree of inclusive fitness then they may be selected to forego their own reproduction entirely reproductive suppression occurs when individuals are inhibited or prevented from reproducing often due to a pressure from the dominant individual of the social group who monopolizes reproduction in clownfish subordinate members of the group don't even develop functioning reproductive systems until the dominant female dies and in meerkats the dominant female attacks and evicts any other females in the group who try to mate as it hampers or even eliminates any chance of the individual achieving any direct fitness reproductive suppression is only viable if the individual stands to gain greater inclusive fitness from helping its relatives reproduce than it would from producing its own offspring as well as high levels of relatedness between group members and highly altricial offspring that are likely to die without many helpers caring for them an important factor that contributes to this is a high cost of dispersal many animals that exhibit reproductive suppression live in environments where patches of resources are separated by stretches of barren or uninhabitable landscape making it less practical for offspring to disperse from the nest to begin their own broods so for the rampadance living in the arid scrublands and deserts near the centre of the western continent the newly matured adolescents may only rarely brave the perilous terrain and myriad predators to attempt to find mates more often remaining within the safety of their mother's burrow to help her raise more offspring plus staying within their home nest also comes with the possibility of inheriting the nest along with privileged reproductive status once the breeding individuals die without having to go to the trouble of establishing their own nest elsewhere which helper ends up becoming the new breeding female will be determined by another form of dominance hierarchy based on age and size with pretendry once again providing a way for males to achieve dominance and if the right ecological circumstances are at play some ramfordon species may specialize to take this bizarre lifestyle to an even greater extreme the ultimate culmination of reproductive suppression is eusociality a form of social organization in which reproduction is monopolized by a small number of breeding individuals who are assisted by multiple overlapping adult generations of their offspring who spend their entire lives tending to the breeders without ever producing any offspring of their own in facultatively used social animals like naked mole rats if the breeding female dies the most dominant helper takes her place and inherits her reproductive privileges but in obligately used social animals like ants bees and termites the helpers remain sterile for their entire lives and if the breeding female dies or runs out of stored sperm then the entire colony ultimately dies as well an individual's role and reproductive status within a eu social colony is referred to as its caste the most basic caste distinction being between helpers or workers and breeders the females of which are usually called queens and the males either kings or drones once again this whole system relies on the workers achieving greater inclusive fitness from helping their mother produce more offspring than attempting to reproduce on their own notably eusociality has evolved in the hymenopterans the ants bees and wasps at least eight times which may at least partially be the result of their haplor diploidy a unique sex determination system in which males inherit only one copy of each chromosome directly from the mother while the females inherit two one from the mother and one from the father which results in a bizarre pattern of asymmetrical relatedness in which the females are more closely related to their sisters than they are to their own offspring however both in the hymenopterans and in new social animals with more typical sex determination systems the maximizing of relatedness between offspring is still largely accomplished via monogamy although many eusocial species revert to other mating systems once you sociality has been established in termites the reproductive male and female the king and queen of the colony remain together and mate continuously to produce a constant supply of workers while in ants the semel paris males die after inseminating the female who is able to store the male sperm for as long as 30 years to keep on producing new generations of offspring as a consequence of so rarely dispersing almost all you social species live in huge communal nests that are usually concentrated around resource-rich areas of otherwise barren habitats the burrowing rampadons may build such nests by digging out huge underground warrens and tunnel complexes feeding on tree roots tylophyte and kryptophyte bulbs malacca forms and any other food they can unearth since they live almost entirely in these lightless underground nests the enormous eyes characteristic of the lystracites are now almost vestigial and so may shrink into barely functioning pits as commonly happens in many fossorial animals their primary sense may come from the mechanoreceptors on their pedopalps which may lengthen into whisker-like structures to help them feel their way through their underground passages on top of adaptations like these many use social species display physiological differences between castes to help them specialize for the role they play in the colony this is usually accomplished through phenotypic plasticity the capacity to undergo physiological or behavioral changes in response to environmental stimuli for instance in their larval stage hokkaido salamanders will adopt either a broad-headed attack morph if there's a local abundance of prey or a large-tailed defense morph if there are lots of predators around unlike evolution which occurs over many generations as a result of changes in gene frequencies phenotypic plasticity occurs within individual organisms and doesn't involve a change in genes but only which of the organism's genes are activated or deactivated phenotypic plasticity provides a way for the different castes of eusocial colonies to physically differentiate in most eusocial species the breeders grow much larger than the workers and have much longer life spans with swollen abdomens filled with expanded reproductive tracts to continuously produce new young in species that specialize for you sociality phenotypic plasticity can also allow the breeders and the workers to differentiate into finer cost distinctions since you social animals depend so heavily on a single nest that provides them with all of their food and shelter they'll need to protect it from predators and other animals that try to raid the nest of its resources so many youth social species have a distinction between normal workers whose main jobs are to care for the young collect food and maintain the nest and soldiers who defend the nest from attackers soldiers are often larger than workers and have bigger heads and stronger jaws to deliver powerful bites in fact in some termites the soldier's jaws are so large and specialized for biting that they can no longer be used for eating and so they have to rely on the workers placing pre-chewed food directly into their mouths in these rampadans the normal workers will have broad spade-shaped claws well suited for digging but those who become soldiers will develop sharp blade-like claws and teeth with which they can aggressively repel any threat that comes near the nest both the workers and the soldiers will spend their entire lives tending to and protecting the enormous queen whose reproduction represents their only means of achieving fitness only a select few young will develop into dispersers the only members of the colony other than the queen capable of reproduction who will leave the nest once they reach maturity to begin new colonies to give them the best possible chance of surviving outside the safety of the nest they may time their dispersal to coincide with the onset of the wet season when resources are most abundant like the nuptial flights of some eusocial insects the male dispersers will spend the rest of their lives seeking out and mating with as many female dispersers from other colonies as they can the few who are lucky enough to avoid being eaten by predators dying naturally once the breeding season ends and the fertilized females will find suitable spots to dig their burrows and begin producing new colonies with a single nest containing over a hundred animals these rampardonts which we'll call eryktochyrids will exhibit some of the most complex social organization of any animal on the planet but even eusociality as astonishingly complex and specialized as it is still isn't the pinnacle of cooperative behaviors if division of labor is extensive enough then the members of a social group may evolve to associate with each other not only socially but also physically in colonial or modular organisms all the members of a colony grow together to collectively form one single super organism in clays like corals pyrosomes and siphonophores what looks like a single individual is actually an entire colony called a genet or zouan composed of many interdependent organisms called remits or zooids much like the castes and eusocial colonies some colonial species have reimages that differentiate into one of a number of specialized morphs that fulfill a specific function in the portuguese manor war one raiment acts as a swim bladder to keep the colony afloat while others catch prey and pass it into yet other raiments that act as stomachs digesting the prey and transporting the nutrients to the rest of the genet and one type of raimet is responsible for producing gametes which are released into the water to eventually encounter gametes from other genets to grow into new colonies since these are the only ramets involved in sexual reproduction the only way for the other reimus to achieve fitness is to work to keep the reproductive ramits alive and healthy so they can propagate the genes they all share achieving inclusive fitness for the whole genet this is reinforced by the fact that in almost all colonial organisms rhemats are produced asexually meaning that all the members of the colony are genetically identical and so they share the same relatedness with any other rhema's offspring as they would with their own so the inclusive fitness they gained from another raiment reproducing is identical to the direct fitness they would gain from reproducing themselves the ability to reproduce asexually is also an ancestral trait among the kemaphites though they can also employ sexual reproduction to increase their genetic diversity and dispersal which some clays like the chromatophytes have specialized for by evolving mutualism with pollinators the earliest chromatophytes were epiphytes growing in tightly clustered asexual colonies along tree branches with the outer surface of their male gametangia covered in long gamete-covered filaments which are brightly coloured to attract the attention of nectarivores the more members of the colony contribute to this colourful display the more visible and alluring they'll be to pollinators making this floral ornamentation not only a form of cooperation but also a marginal instance of altruism since one plant's display will increase the likelihood of other members of the colony being pollinated as well which they can afford to do since all the members of the colony share the same genes and if this tendency for colonial cooperation continues some of the subsequent chromatophyte clays may evolve into full-fledged colonial organisms evolving division of labor among the members of the colony and differentiation into specialized reimus some will serve as structural support growing into a sort of stem to reach upward for light some may spread along the ground like roots to gather water and nutrients some may feel the function of leaves distributing the sugars they produce from photosynthesis to the rest of the colony and some may specialize into reproductive structures the only members of the colony to produce gametes and to be involved in pollination these colonial plants which we'll call zygophytes will be more adaptable than most plants thanks to their flexible body plan and so will become successful ground plants in tropical areas rapidly spreading thanks to the mutualism they've maintained for their pollinators and seed dispersers in a way colonial organisms like these can be seen as analogous to the evolution of multicellularity all multicellular organisms are associations of interdependent cells each of which differentiate into one of many different kinds of cell to carry out a specific function all working together to keep the super organism the individual alive but only the sex cells will actually be involved in reproduction and will be the only ones to pass on their genes and the genes they share with the other cells of the superorganism to a new individual so in a way all multicellular organisms even solitary ones are examples of sociality in action the possibilities for cooperative behaviors are almost limitless in their variation and complexity but the clades we've looked at here will exemplify some of the more common ways for sociality to manifest evolving within the time between the first glacial periods up to about 30 million years following the end of the ice age but shortly after this point the adaptations of all of the mainland clays will be put to the test in the face of a new challenge in the next episode we'll explore the ecological upheaval that occurs when the two continents merge back into one thanks again to all the artists on discord who contributed artwork for this episode and who saved me an enormous amount of time and effort when making these videos while simultaneously making them look a hell of a lot better in the process links to the main server and the alien biosphere's fan server in the description and once again a massive thanks to all the patrons whose continued support makes videos like this possible thanks for watching and i'll see you in the next video [Music] [Music] so [Music] [Music] [Music] [Music] [Music] you