Topic 7- Life history patterns – Flashcards
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Life history
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an organisms lifetime pattern of growth , development, and reproduction
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Parthenogenesis
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a form of asexual reproduction in which the ovum develops without fertilization by a male.
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Monogamy
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involves the formation of a lasting pair bond between one male and one female
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Polygamy
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The acquisition by an individual of two or more mates.
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Polygyny
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a male pairs with two or more females
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Polyandry
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a female pairs with two or more males
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Promiscuity
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males or females mate with one or many of the opposite sex and form no bond
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Simultaneous hermaphrodite
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the male organ of one individual is mated with the female organ of another individual and vice versa. (Results in a population of hermaphroditic individuals.)
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Sequential hermaphrodite
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an individual that changes sex as the individual matures or grows larger. A change in the sex ratio of the population stimulates sex change among some animals.
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intrasexual selection
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involves male-to-male (sometimes female-to-female) competition for the opportunity to mate. Leads to exaggerated secondary sexual characteristics such as antlers and horns.
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Intersexual selection
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involves the differential attractiveness of individuals of one sex to another. Characteristics include bright colors used in sexual displays.
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Sexual dimorphism
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the occurrence of morphological differences other than primary sexual characteristics that distinguish males from females in a species.
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Leks
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small groups based on communal courtship. Males defend small territories that hold no resources and advertise their presence by colorful vocal and visual displays.
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Iteroparous
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organisms that reproduce fewer young at one time and repeat reproduction throughout their lifetime
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Semelparous
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an organism sacrifices future prospects by expending all its energy in one suicidal act of reproduction.
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Fecundity
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potential ability of an organism to produce eggs or young, rate of production of young by female. The number of offspring produced depends on age and size of parent
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logistic growth equation
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mathematical expression for the population growth curve in which rate of increase decreases linearly as population size increases. r is the per capita rate of growth, and k is the carrying capacity (maximum size a population can sustain)
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r strategists
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have short lives, they have high reproductive rates at low population densities, rapid development, small body size, large number of offspring (with low survival), and minimal parent care.
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K strategists
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competitive species with stable populations of long-lived individuals. They have a slower growth rate at low populations, but they maintain that growth rate at high densities.
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Grime's model of life history variation
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life variation in plants based on three primary strategies: ruderals (R), competitive (C), and stress-tolerant (S).
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R-species
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rapidly colonize disturbed sites. Species are typically small in stature and short-lived. Allocation of resources is primarily to reproduction, with characteristics allowing for a wide dispersal of seeds to newly distributed sites.
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C- Species
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species that inhabit predictable habitats and allocate resources to growth, favoring resource acquisition and competitive ability.
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S-species
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species that inhabit areas with limited resources, and allocate resources to maintenance.
