9 population Flashcards
what is Population
A population is a group of individual organisms of the same
species occupying a defined space which share many characteristics as Morphological, Physiological, Behavioural
Charles Darwin’s theory of natural selection
*The disparity between numbers produced
and that which can be supported by the
available resources results in a struggle for existence
*In the process of natural selection some members of a population are more likely to survive and have offspring than other members deemed less fit
*Variation, inheritance and competition are the key points in natural selection
describe Genetic variation in Populations
*Genes are located on chromosomes, made up of DNA
The genetic composition of an organism is genotype
*The genotype of living organisms are responsible for the growth, development, maturation and reproduction of individuals.
*the phenotype is the outcome of the effect of genotype and the environment
What is ecotypes?
Several populations display phenotypic traits along
environmental gradients result from genetic adaptations
Reproduction
*Asexual reproduction (results in genetically identical offspring) and Sexual reproduction affects the amount of variation
*asexual results in genetically identical offspring, reproduction
is rapid and so the environment can be maximally exploited. However, If there is a change in environment, it can be a disadvantage.
*Sexual reproduction, the production of a zygote during
fertilization from the fusion of two gametes which may
come from the same individual (self- fertilisation or inbreeding)
or from different individuals (cross-fertilisation or
outbreeding)
what is a community
a dynamic aggregation of populations of different species, Communities are characterized by the habitat or by the dominant species
what is Habitat and Niche
A habitat is the physical space where an organism lives and obtains resources, Each habitat comprises a collection of niches, a unique location occupied by a particular species in a community
what is patchiness
The most notable feature of the local distribution patterns of populations and communities, a result of the uneven spatial
and temporal distribution of resources in ecosystems
what is keystone species
have a critical role in some communities and changes in their abundance cause major changes in the community structure, Dominant species may exert strong control over the occurrence of other species
e.g.the beaver shape the freshwater ecosystem through its damming activities, which shape and sustain wetland ecosystems
how a species become dominant
1.Rapid colonisation by opportunistic species of a new resource in a habitat
2.A species specialising in a widely distributed and abundant resource
3. A species becoming a generalist so it can utiliz resources of a wide variety recource
what is biotic potential
The inherent ability of a population to reproduce and
increase in numbers, its maximum reproductive power, does not exist in reality
what is Carrying Capacity
The limit to the biotic potentia, the maximum size of a particular population under environmental resistance