plsc 214: adaptation and natural selection

adaptation

genetically determined characteristic that improves an organisms ability to survive, grow and reproduce under prevailing environmental conditions

most fundamental constraint on life

• energy aquisition

• autotrophs: primary producers. derive energy from sunlight

• heterotrophs: secondary producers. derive energy by consuming other organsims

genecology

study of genetic variations (and adaptations) between populations of a single species subjected to various ecological factors which control their speciation

speciation

process by which new species come into existence

genotype

sum of the hereditary information carried by the individual which directs development and produces the individuals morphological, physiological and behavioural makeup

Phenotype 

external, observable expression of genotype

phenotypic plasticity

the ability of a genotype to give rise to a range of phenotypic expression under different environmental conditions

acclimation

a plastic, temporary change in an organism caused by an environment to which it has been exposed in the past

ecotype

- genetically distinct strain of a population adapted to its

unique local environmental conditions

- capable of interbreeding with other ecotypes of the

same species but usually prevented by ecological barriers

natural selection

• differnetial success (survival and reproduction) of individuals withing the population, and the product of two conditions:

-variation in heritable characteristics

-differences in indivifual survuval and reproduction

darwin

• English naturalist who proposed the theory of evolution by natural selection, emphasizing the role of adaptation and variation in species.

• studied finches on galapagos islands to see genetic variations between guilds, finding that they were dependent on energy (food) source available

stabilizing effect

favours the phenotype near the population mean value of the trait

directional effect

favours one extreme phenotype, occurs under environmental stress

disruptive effect

favours both extreme phenotypes simultaneously- occurs under different selection pressures in different environments, usually resulting in a population containing two or more phenotypes

polymorphism

• phenomenon of distinct forms of a species in the same habitat at the same time resulted from disruptive selection

fitness

• ability of an orgnaism to accomplish reproduction successfully, measured by the relative number of successful offspring left by an individual

minimum viable population:

hreshold level of population ( minimum number) to ensure the persistence of a subpopulation

evolution

process by which the properties of populations change over generations

inbreeding

• mating between relatives often due to small populations in close proximity of potential mates, ecological preferences etc.

• reduces genetic variability

• rare in nature (except for self-fertilizing plants)

inbreeding depression

• consequences of inbreeding can result in decreased fertility, loss of vigor, reduced fitness, even death

• spatial separation provides safeguards against inbreeding depression

outbreeding

• mating between unrelated individuals, often taking place in large areas, between individuals from different populations of the same species

• often aided by pollinators who bring pollen grains from different plants

outbreeding depression

occurs when each parent is adapted to their own environment, but the offspring are poorly adapted to either environment

morphological classification

• binomial nomenclature created by Carl Von Linne

• based on morphology, or structure and form, as well as specific features of a species

biological classification

• expansion on the classical Linnaean system taking into consideration the

darwinian idea of common acestry

• a heirarchy is created based on rank

habitat

• the location or place an organism lives, or the environment in which a

community of a certain species is found

niche

• the role and function of an organism in a community, including the organisms activities and relationships with other organisms

• each species occupies a different niche within the community

• niches are separated based on spatial, temporal or functional relationships

• the amount of niche overlap is influenced by the amount of

competition for that resource

generalists

species that can thrive in a wide variety of environmental conditions and can utilize a range of resources.

wide range of tolerances, therefore occupying a large (broad) niche

specialists

• species that require specific environmental conditions or resources to survive, often occupying a narrower niche.

• highly localized

• vulnerable to changes or peturbations that adversly affect their niches

• can be used as indicators of site quality in reference to pollution levels etc.