Topic 7- Life history patterns

Topic 7- Life history patterns

Life history
an organisms lifetime pattern of growth , development, and reproduction
Parthenogenesis
a form of asexual reproduction in which the ovum develops without fertilization by a male.
Monogamy
involves the formation of a lasting pair bond between one male and one female
Polygamy
The acquisition by an individual of two or more mates.
Polygyny
a male pairs with two or more females
Polyandry
a female pairs with two or more males
Promiscuity
males or females mate with one or many of the opposite sex and form no bond
Simultaneous hermaphrodite
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.)
Sequential hermaphrodite
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.
intrasexual selection
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.
Intersexual selection
involves the differential attractiveness of individuals of one sex to another. Characteristics include bright colors used in sexual displays.
Sexual dimorphism
the occurrence of morphological differences other than primary sexual characteristics that distinguish males from females in a species.
Leks
small groups based on communal courtship. Males defend small territories that hold no resources and advertise their presence by colorful vocal and visual displays.
Iteroparous
organisms that reproduce fewer young at one time and repeat reproduction throughout their lifetime
Semelparous
an organism sacrifices future prospects by expending all its energy in one suicidal act of reproduction.
Fecundity
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
logistic growth equation
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)
r strategists
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.
K strategists
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.
Grime’s model of life history variation
life variation in plants based on three primary strategies: ruderals (R), competitive (C), and stress-tolerant (S).
R-species
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.
C- Species
species that inhabit predictable habitats and allocate resources to growth, favoring resource acquisition and competitive ability.
S-species
species that inhabit areas with limited resources, and allocate resources to maintenance.