chapter 11 part 2 Flashcards
Eurasian penduline tit parental care behaviors
within the same population may include maternal, paternal, and biparental care; evidence in favor of the idea that those with a good body condition are the ones to desert
what is the fundamental asymmetry of sex
differences from the beginning in parental investment, illustrated by the costly egg produced by females and the minimally costly sperm produced by males
European earwigs
benefit to parental care is feeding hatched larvae (aiding their survival and the parents reproductive success partially); cost - staying with eggs for one week greatly reduces reproductive success compared to females who leave immediately to produce another, new batch of eggs
Costs and benefits among polyandrous species
multiple matings increase value of offspring for females and reduces costs of losing out on additional mating opportunities while providing parental care
For males; caring for a brood reduces his reproductive success because only some of those offspring sired by a polyandrous female may be his
paternity assurance hypothesis
males are more likely to provide parental care when they are certain to be the fathers of those offspring (unlikely among polyandrous species then..)
ex. dunnock - a species that can be both monogamous and polyandrous; males in monogamous relationships only lessen parental care provided if his mate participated in extra pair matings; among polyandrous matings the males already know they have less of a probability of having sired all offspring and thus there is no difference in parental care and levels of paternity
what is the ancestral state of parental care in poison frogs
paternal care
paternal care is beneficial because of male territoriality and guarding of safe places to lay eggs
Examples of paternal care species
st. peter’s fish, neotropical poison frogs; harvestman spiders
Polyandry is (rare/common) in birds
rare
found mostly in waders and shorebirds
if a (bird) species is polyandrous - there is sex role reversal and male only parental care (ex. northen jacanas)
water bugs parental care
oxygen and moisture necessities for eggs led to evolution of back brooding (typically male brooding)
evolved because they lay typically large eggs; cannot lay smaller eggs because of the size needed to acquire in order to kill prey; cannot molt more than five times an each molt only allows a 50-60% growth expansion, so this species must begin large (as eggs)
also tends to be males because they may have additional fitness benefits/reproductive benefits by appearing appealing while already caretaking a brood of eggs
Offspring recognition
ex. mexican free-tailed bat - nurse own offspring apprx 80% of the time after returning to many hungry pups of seemingly indeterminate genes
ex. common degu - communal burrows/common parental care
ex. subantarctic fur seal - mothers stay and tend to pups for one week before leaving on an up to 3 week fishing trip; pups learn their mothers voices within 5 days and upon mothers return they call to each other and reunite within 15 minutes
offspring recognition functions to prevent misdirected care
bank swallows, a colonial species, highly adept at recognizing the vocalizations of their own offspring vs. others.
solitary rough-winged swallow, a solitary nesting species, have no need for significant offspring recognition mechanisms.
cliff swallow(colonial species) vs. barn swallow (less social) - more vocal variability among the colonial cliff swallow species in comparison correctly IDing their own offspring 85% of the time
interspecific brood parasites
when an animal exploits the parental care of individuals of another species
ex. common cuckoo - kills all of host families offspring and the chick that replaces them then mimics that foster parent species’ entire brood signaling need for an entire broods’ worth of food/resources
ex. brown headed cowbird - won’t kill offspring of host parents but instead benefits from their presence.
ex. cucukoo bees
why do species accept parasitic eggs?
may be the more adaptive option (vs. risking killing ones own offspring)
more common when the host is a small species (parental favoritism towards the largest leaves them vulnerable to larger parasite species)
cost of building new nest or of generating a new brood may be exceptionally high (especially in species who use tree cavities to build their nests)
mafia hypothesis
hosts accept brood parasitic eggs out of fear of retaliation by the brood parasite for destroying its egg
ex. great spotted cuckoos and its host species European magpie - those who accepted cuckoo eggs had less predation (12%) than those who ejected cuckoo eggs (87%) by returning cuckoo adults and thus receive greater overall reproductive success by accepting parasitic eggs
Parasitic parents choose a host
nest chosen affected by size of the nest, size of the eggs already in the nest; single host species and host generalists (will lay in many different species’ nests)
greater honeyguide has two separate types of parasitism - ground vs. tree nesting species; a preference trait that is passed in the mitochondrial DNA from mothers to daughters
coevolutionary arms race
when two parties in conflict exert reciprocal selection pressure on each other, with an adaptive advance made by one often leading eventually to an adaptive counter response by the other
Unique host egg signatures make it ______ for hosts to recognize parasitic eggs and _______ for parasites to produce mimetic eggs
easier; harder
unique egg signatures have led to….
better protection against host species, better mimicry on behalf of parasitic species; more thorough parasitism on behalf of the parasitic parent (more parasitic eggs create higher risk of ejecting wrong eggs)
parasitic bronze cuckoo and host superb fair-wren
if the cuckoo lays an egg before the wren does then the wren will build a nest on top of it; if the cuckoo lays an egg after the wren lays an entire clutch the the wren will leave and produce a new clutch; if the cuckoo lays an egg in the middle of a wren’s clutch production then that egg tends to be accepted
after the eggs hatch - the cuckoo kills off the host siblings and the host parent abandons the nest 40% of the time leaving the cuckoo infant to starve
cuckoo specialist parasitic evolution
has evolved 3x; ancestral state were parents who cared for their own offspring –> parasitizing same species nests –>shift to 1+ species next…eventually evolved from species types with large home ranges and migratory tendencies
conspecfic (intraspecific) brood parasitism
when an animal exploits the parental care of individuals of their own species
gradualist shift hypothesis
the evolution of interspecific brood parasitism involved intraspecific parasitism as an intermediate stage
intraspecific parasitism examples
zebra finch, american coot, wood ducks - females lay eggs in the same tree cavity and the “winner” ejects the loser who becomes an unwilling parasite whose eggs are now cared for by the winner
“losing” may become adaptive if they’re then able to go lay another brood; example Barrow’s goldeneye
may be explained by several hypotheses as to potentially benefits of brood parasitism
