Chapter 8: Life History Patterns (Exam 1) – Flashcards
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life-history
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traits that describe the life cycle of an organism (reproductive rate, maturity rate, lifespan etc.)
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asexual reproduction
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one parent passes on a complete set of genetic info (binary fission) less genetic variation-no mate needed
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sexual reproduction
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2 parent s each pass on 1/2 set of genetic info reproduction costly but greater variation
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parthenogenisis
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development of an individual from an unfertilized egg (lizard)
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simultaneous hermaphrodite
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has both male and female reproductive structures at the same time
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sequential hermaphrodites
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spend part of their life cycle as a female and part as male (mollusks, echinoderms)
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hermaphroditic
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possessing both male and female reproductive organs
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mating systems
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monogamy polygamy polygyny polyandry
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monogamy
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1 female/1 male w/long lasting bond (birds)
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polygamy
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2 or more mates (cats)
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polygyny
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form of polygamy where 1 male pairs w/2 or more females (moose)
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polyandry
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form of polygamy which 1 female pairs w/2 or more males (sand pipper)
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sexual selection
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mate choice and competition for mates among individuals may lead to selection for particular traits
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intersexual selection
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members of 1 sex consistently choose mates of the opposite sex based on certain traits
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intrasexual selection
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individuals of one sex compete among themselves for mates
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secondary sexual characteristics
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not directly involved in reproduction (differences in phenotypes)
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runaway selection
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members of opposite sex find a trait desirable "runaway" because over time it would facilitate the development of greater preference and more pronounced traits until the cost of trait balances reproductive benefit of possessing it
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life-history adaptations
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increase of reproductive effort may benefit offspring but can reduce survivorship of the parent
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reproductive effort
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the amount of energy allocated to reproduction
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clutch size
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number of offspring per reproductive eent
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clutches per year
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environmental variation yearly & seasonal variation latitudinal and elevational variation (clines)
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semelparity
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having only a single reproductive effort in a lifetime over one short period of time
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iteroparity
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many reproductive events per lifetime
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bet-hedging
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unpredictable environments (lean forage) delay reproduction, survival of parents, abandonment of the eggs or offspring
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neoteny
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reproductively active as larvae (tiger salamander)
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altricial
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short incubation times often result in young being born in helpless state, which requires greater parental care
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precocial
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longer incubation periods can produce young which require considerably less parental care
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reproductive strategies
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placental mammals marsupials oviparous ovoviviparous viviparous
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paedomorphosis
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The retention in an adult organism of the juvenile features of its evolutionary ancestors.
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placental mammals
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give birth to live young (r or precocial) who received their nourishment during embryonic development from allartoic placenta
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marsupials
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give birth to live young who complete their embryonic development inside a maternal pouch called marsuprum which contains nipples for nursing
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oviparous
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lay eggs w/little or no other embryonic development w/in the mother (yolk sac provides nourishment)
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ovoviviparous
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young develop w/in eggs or membrane sacs that remain w/in the females body until they hatch (or are able to)
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viviparous
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birth to live young (reptiles, fish)
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life-history adaptations
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characteristics exhibited by a species are the product for evolution and should reflect adaptations to the prevailing environmental conditions under which natural selection occurred
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r-strategist
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(typical (short lived)), high reproductive rates at low population densities, rapid development, small body size, large # of offspring (but low survival rate), minimal parental care
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K-strategist
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competitive species with stable populations of long-lived individual can cope w/physical and biotic pressures
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opportunistic life-history
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low offspring survival, low birth rates, early maturity
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periodic life-history
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low offspring survival, high birth rates, late maturity
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equilibrium life-history
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high offspring survival, low birth rates, late maturity
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gonadosomatic index (GSI)
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index of reproductive effort
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synchronous hatching
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Hatching that occurs at the same time or nearly the same time, usually within one calendar day (compare to Asynchronous Hatching).
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asynchronous hatching
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A hatching that does not occur at the same. It may take place over two to three calendar days. Parrots hatch Asynchronously while ducks and chickens hatch Synchronously.
