Lecture 8- Reptiles 5 (Social life) Flashcards
What is the following in the visual, auditory and olfactory signals?
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What are the visual signals in jacky dragons?
-tail flick attracts attention -must be conspicuous against moving vegetation -works best when longer lasting -Signal duration in calm vs windy vegetation?
What about colour signals in lizards?
-can see UV so what looks to us as one colour will be more to them -eg, ornate dragons, on the bottom of their belly they have markings, males= we can see, females= can’t see as it is two types of white (UV and normal), in an experiment it’s been shown that males prefer females with more UV
What are some examples of vocal signals in reptiles?
-gecko vocalisation -purpose varies with species -the use in Diplodactylus damaeus = serve as aggression between males, try to bite, rape etc. -Gehyra variegata= protection against predators -Hemidactlyus frenatus= the clicking sound ttttt -use the calls in territorial disputes -when they eat an insect -male to female interactions, many other social situations
How do olfactory signals work in reptiles? How do they smell?
-tongue collects chemicals -deposits chemicals in the vomeronasal (Jacobsen’s) organs -these organs are lined with nerve endings that lead to accessory olfactory lobe of the brain -most reptiles use olfactory cues -femoral pores= release chemicals through the bottom of their leggs= used as territorial markers
What is the predominant social behaviour in reptiles?
-solitary -polygamous -no parental care
Which groups differ in their social life and how?
-Social behaviour has evolved independently in numerous reptile groups (e.g. skinks, geckos, snakes) - Aggregation -Rudimentary parental care -Stable social groups
What is special about the Egernia group?
-approx 30 species, long lived and many of them show complex social behaviour
What types of social behaviour do the Egernia group lizards exhibit?
-stable social groups -social monogamy (throughout their lives, between breeding seasons)= the genetic father not necessarily the social one -family groups(as they are all live bearers and the juveniles stay with parents= delayed juvenile dispersal) -rudimentary parental care
What is the social structure in White’s skink?
-71% groups consist of pair (29% social groups with >1 adult female) -Stable pair bonds (approx. 75% with same partner following season) -39% of social groups with one or more juveniles or sub-adults -Juveniles/sub-adults were the genetic offspring of the resident pair (75% of cases) -Extra-pair paternity (34%) (another father)
How big do the groups get in skink species?
-Egernia whitii (2-6 individuals) -Egernia stokesii (up to 17 individuals) -Egernia saxatilis (up to 14 individuals but usually ‘nuclear families’) -Egernia cunninghamii (up to 26 individuals)
What is sociality facilitated by?
-Recognition of individuals, -Recognition of familiar/unfamiliar individuals (recognition of group or non group members) -Recognition of related/unrelated individuals
Can White’s skinks recognize their kin?
-measured the home ranges of individuals, the male one did not include the social offspring, only the genetic offspring -Males do not tolerate offspring of other males in their home range -Indirect evidence for kin recognition
How did they determine kin recognition in tree skinks?
-using the chemicals released from the femoral pores and their poo (scats) -put paper towels with the chemicals and then the poo and measured how much time they spent investigating the smell -with paper towel= more time spent investigating non-self smells and more time spent investigating distantly related than closely related -the poo= more time on non-self smells but no distinction between close or distant relatives= so can’t tell the kin by poo smell but can by the femoral pore chemicals
How did they test the kin recognition in tree skinks using basking time and aggressive acts?
- more time spent basking with closely related than distantly related
- more aggression towards distantly related individuals then closely related
What are scat piles used as?
-often used as territorial markers (Some Egernia species scat pile)
How did they test if scat piling is used for individual/group/species recognition?
- 2 species types of skinks, tree skink(scat piles) and desert skink (doesn’t scat pile)
- 3 pieces to test= self (own poo), heterospecific (poo of different species) and unfamiliar specific (member of the same species= but haven’t met)
- RESULTS:more time investigating unfamiliar smells than their own but no difference between the same species or different species= support theory that they can’t tell the diff from poo
How did they test the recognition of group vs non-group individuals in gidgee skinks?
- using both scats and paper towels with the femoral pore chemcials
- self, group member and non-group member poo and chemical
- RESULT: same for paper towels and poo -same result for related and unrelated group= therefore the main thing is if they are both in one group
- to test this further they put the chemicals and scats of related in group and related out of group to test if it were genetically affected.
- RESULT: can’t distinguish related and unrelated= it is the group or ougroup that matters!
What are the costs of sociality?
-Increased competition for resources -Increased probability of detection by predators -Increased transfer of disease and parasites
What are the benefits of sociality?
-Increased vigilance -Physiological benefits (e.g. reduced heat or water loss= huddling reduces this) -Parental care/protection
How is vigilance in gidgee skinks influenced by being a part of a group?
-much more time spent in non-vigilant behaviour when in group then when alone
How do you measure vigilance in reptiles?
-walk towards them and when they fled= what distance where they away from you
What was the experiment about juvenile aggression towards juveniles in black rock skinks?
- High aggression to juveniles, particularly when unrelated
- much higher aggression towards juveniles who are unrelated
What suggests that parental care protects against adult aggression in black rock skinks?
- the aggression directed at juveniles who are in the presence of their mother is much lower than when they are with unrelated adult/adults
- the aggression can result in death so by parental care the parents are ensuring higher survival rate for their offspring
What are the factors in evolution of sociality? Why does it happen?
-Ecological factors promoting sociality —–Aggregation occurs when access to key resources (e.g. shelters, food) is limited because they are clumped in space or time —-Limited resources can favour the evolution of territoriality and social groups -Life-history traits promoting sociality ——Long life span and long period until reproductive maturity may favour delayed offspring dispersal
What is the evidence for the factors involved in the evolution of sociality?
-Within species, variation in habitat (e.g. E. striolata) is correlated with social behavior and aggregation -But evidence for the importance of ecological factors in explaining variation in sociality between species is mixed -All species examined so far are long lived and have delayed juvenile dispersal so the role of life-history is difficult to assess
Who can tree skinks, black skinks and gidgee skinks recognize?
-Tree skinks appear to recognise related individuals, but gidgee skinks and black rock skinks are mainly able to distinguish familiar/unfamiliar individuals irrespective of relatedness.
