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
Why complex life styles?
Parents and offspring can be subject to different selection pressures
Butterfly
Direct development -
Go from fertilized egg to juvenile without passing through a specific larval stage
Seepage salamander
Alternation of generations:
- exhibited by plants and most algae
- multicellular diploid sporophyte alternates with a multicellular haploid gametophyte
Reproductive patterns can be categorized along several continua.
Semelparous - iteroparous
r-selection - K-selection
Stress - disturbance
Charnov’s life history cube
___ species reproduce only once.
Semelparous
___ species can reproduce multiple times.
Iteroparous
Almond tree
Semelparous species include:
- annual plants
- agave
- giant pacific octopus
- salmon
Iteroparous species include:
- trees such as pines and spruces
- most plants and many herbaceous plants
- most vertebrates
- mane invertebrates
- Florida scrub jay
r-selection and K-selection describe…
Two ends of a hypothetical continuum of reproductive patterns
r =
Intrinsic rate of increase of population
K =
Carrying capacity for a population
r-selection is selection for…
High population growth rates in uncrowded environments, newly disturbed habitats, uncrowded contains, etc
K-selection is selection for..
- slower growth rates in populations that are at or near K
- in crowded, more stable conditions, efficient reproduction is favored
___ is a spectrum of population growth rates, from fast to slow.
r-K continuum
On the r-selected end
- short life spans
- rapid development
- early maturation
- low parental investment
- high rates of reproduction
- most insects, small vertebrates such as mice, weedy plant species
Live fast, die young
On the K-selected end
- long-lived
- slow development
- delayed maturation
- invest heavily in each offspring
- low rates of reproduction
- large mammals, reptiles such as tortoises and crocodiles, and long-lived plants such as oak and maple trees
Slow and steady
Stress -
Any factor that reduces vegetative growth
Disturbance -
Any process that destroys plant biomass
“CSR” model
Competitive, stressed, ruderal
