Ch. 7 Life History Analyses Flashcards
Social control of sex change
Clownfish
- If the female dies, the breeding male becomes a functional female
- next largest male becomes breeding male
- controlled by female aggression
- suppression of hormonal and neurotransmitter control of sex change in subordinate males
- breeding male cares for eggs until they hatch
Sequential hermaphroditism
- protandry
- protogyny
Protandry
Males first
Protogyny
Females first
There is a strict ___ or ___ ___ in the group, based on body size and aggression.
Social or dominance hierarchy
Life history -
An organisms record of events relating to its growth, development, reproduction, and survival
Characteristics that define organisms life history:
- age and size at sexual maturity
- amount and timing of reproduction
- survival and mortality rates
Generalizations about a species life history traits can still be made but must consider ___.
Variations
Life history strategy of a species:
- overall pattern in average timing and nature of life history events
- determined by allocation of time and energy between growth, reproduction, and survival
___ are parts of a strategy
Traits
___ refers to overall patterns at the species or population level.
Strategy
Theoretically life histories are optimized by ___ ___.
Natural selection
Phenotypic plasticity
- One genotype may produce different phenotypes under different environmental conditions
- many fishes develop different body shapes dependent on habitat
- pines grown in cool, moist climates allocate more biomass to leaf growth relative to sapwood production than do those in warmer desert climates
Phenotypic plasticity may result in..
- continuous range of growth rates
- discrete types (morphs)
Polyphenism -
Single genotype produces several distinct morphotypes
Allometry -
Differential growth of body parts, resulting in differences in shape or proportion
Asexual reproduction -
- simple cell division
- exhibited in all prokaryotes and many Protists
Benefits of sexual reproduction:
- recombination promotes genetic variation
- increased ability of populations to respond to environmental challenges
- may provide protection against disease or changes in habitats
Disadvantages of sexual reproduction
- “cost of males” - an individuals transmit only half of its genome to next generation
- growth rate of populations is slower
C. elegans
- either male or hermaphrodite
- hermaphrodites can reproduce by self-fertilization (selfing) or mating with males (outcrossing)
Isogamy -
When gametes are of equal size
Organisms such as the green alga produce isogametes
Anisogamy -
Gametes of different sizes
Most multicellular organisms produce anisogametes
Metamorphosis -
Abrupt transition in form from larval to juvenile stage
Complex life styles -
Involve at least two distinct stages that may have different body forms and live in different habitats