Ecology Exam 3.1
Polygyny
1 male, many females
males compete for females
prevalent in mammals, many males never mate
females supply food
Female Choice Handicap Principle
Theory by A. Zahavi(1973)
the traits that get selected represent a handicap, so they will be more fit
Immunocompetence
secondary sexual characteristic, sometimes a result of levels of testosterone
Polyandry
many males, 1 female
rarest system, prevalent in birds
response to extreme environmental conditions
Promiscuity
many males and females
amphibians and fish
Influences on Mating Systems
environmental, social, and physiological factors
Population
grp of individuals of same species, living together
Population Characteristics
distribution(habitat preference/range)
density
sex structure, age structure
a common gene pool
The Biological Species Concept (Mayr 1969)
a group of interbreeding, natural population that is reproductively isolated from other groups
The Recognition Species Concept
a group of organisms with a common method of recognizing and responding to mates
Allopatric Speciation
a population formation that requires geographic isolation
Sympatric Speciation
a population formation that occurs within the range of ancestral species, isolation is not required
Effects of Fragmentation
Crowding, Competition for Resources, Extinction or Migration, # of Original Species Decline
Ecology Community
association of plants and organisms whose distribution coincides with each other
Community Processes
these characteristics are dynamic and influence community structure
Persistence
length of time a community characteristic lasts before it changes as a result of an influence
Resistance
once a characteristic is changed, how do other characteristics respond
Resilience
how fast a characteristic that has changed returns to the previous state
Variability
how much does a characteristic vary over time
Connectance
degree of interdependency of community components
Colonization/Extinction
process of establishment of community components and subsequent fate
genetic drift in a small pop increases chance of extinction
i.e. island biogeography
Succession
continuous, undirectional, sequential change in the species composition of a community
frequently in response to a disturbance
Keystone Predation
top predator controls community composition
Stages of Succession
1.Grasses
2.Woody Vines
3.Shrubs
4.Trees
5.Climax Community
***SERE is each stage up to Climax (1,2,3,4)***
As stages progress, soil becomes more fertile/deeper
Keystone Species
not high in biomass, yet have a high influence on the community structure
Dominant Species
make up most of the weight in the forest and take up most the space
Community Characteristics
1.Species abundance
2.Species diversity
3.Habitat structure
4.Ecotones
5.Ecological gradients
Ecotones
a meeting place or border between 2 community types, characterized by relatively high species diversity
Mechanisms of Facilitation
1.Zebras feed first, remove coarse, less nutritous plants(hind-gut fermentation can’t take advantage of nutritous plants)
2.wildebeast move in next tall grasses (have ruminant stomach, use nutritous plants)
3.Thompson’s Gazelles eat the small broad leaved plants made visible by previous grazers
Bioindicators
1st ones used were hawk, falcon, and eagle eggs; DDT present caused eggshells to thin
Endocrine Disruptors
results from the intro of hormones and antibiotics into the environment; biggest source is cattle, excreted in urine
Chytrid Fungus
responsible for killing large numbers of amphibians
Vulnerability Characteristics
Specialized habits, large size, small population, dependence on staging areas, valued by humans, environmental sensitivity
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