Niche and Evolution Flashcards
What is a Niche?
the environmental conditions (abiotic and biotic) in which an organism can survive, grow and reproduce
What is the Hutchinsonian Hypervolume?
the huntchinsonian niche describes a species niche as hypervolume along multiple axes of environmental variables
Ecological Niche Modeling
niches are often calculated to predict potential geographic distribution ranges
What is the Principle of Allocation?
- the amount of energy available to each organism is limited
- when energy is allocated to one function, it reduces the energy available for other functions
What are energy budgets?
within its niche. an organism has a limited amount of energy available that it takes up via food/photosynthesis
no matter the organism, energy acquired must be used for:
- growth
-maintenance
-activity
-reproduction
Competitive Exclusion Principle
Gause’s Law
- two species cannot coexist if their niches are the same
- competition may play a role in defining the realized niche
What is niche partitioning ?
when a species in a community use limiting factors in different ways (i.e., the occupy different niches)
Define Evolution
change in allele (i.e., gene) frequencies within a population over time
Darwin’s Finches
- finches on the archipelago resembled mainland finches
- species on the archipelago differed in their morphology, especially in beak size and form
- darwin later concluded that natural selection may be the mechanism underlying evolution
What is fitness?
an individuals’ relative genetic contribution to the next generation’s gene pool
What are Alleles
different forms of a gene (A,a)
What is a gene pool
the sum total of all the alleles in a population
What are diploid organisms
one with two alleles of a gene
Phenotype
an attribute of an organism, such as its behaviour, morphology or physiology
Genotype
-the set of genes an organism carries
-one genotype can produce several different phenotypes, depending on how genes are expressed
What Causes phenotypic variation among individuals within a population?
- genetic differences
- environmental factors
Phenotypic Plasticity
the ability of one genotype to produce more than one phenotype when exposed to different enviornments
Mechanisms of Evolution
changes in gene frequency within a population occur via natural selection and random processes
Random processes include
- genetic drift
- bottleneck
- founder effect
What is the Hardy-Weinberg Principle
- in an infinitely large population where mating is random and evolutionary forces absent, allele frequencies will remain constant across generations
What are some ways the Hardy-Weinberg equilibrium can be disturbed?
mutations, natural selection, non-random mating, genetic drift and gene flow
Genetic Drift
a process that occurs when genetic variation is lost because of random variation in mating, fecundity, morality, and inheritance
Bottleneck
a reduction in genetic diversity in a population due to a large reduction in population size
Founder Effect
a small number of individuals leave a large population to colonize a new area and bring with them only small amount of genetic variation
Natural Selection
- many offspring are produced, not all survive
- traits vary among individuals within a population and may be heritable
- some heritable traits give individuals an advantage
- advantageous traits, conferring higher fitness, become more common
Directional Selection
natural selection that appears to shift phenotypic variation into specific direction (favouring extreme phenotypes)
Disruptive Selection
two or more extreme phenotypes become more frequent and the average phenotype becomes less frequent
What is Speciation
the outcome by which species evolve due to physical and ecological processes that interact with natural selection and random processes
Biological Species Concept
- Ernst Mayr
- groups of actually or potentially interbreeding populations, which are reproductively isolated from other such group
Reproductive Isolation
mechanisms of reproductive isolation before zygote can be formed, such as through geographic isolation, temporal isolation, behavioural isolation, mechanical isolation
allopatric speciation
occurs when a single population becomes spatially subdivided into multiple subpopulation
sympatric speciation
occurs when a population is not spatially subdivided and interbreeding fails due to non-spatial isolating mechanisms, such as positive assortive mating
Parapatric Speciation
- when a population expands into new habitat within the pre-existing range of the parent species and the offspring of these two subpopulations fail to reproduce due to spatial segregation, dispersal limitation, non-random mating,etc
- sometimes considered a form of allopatric speciation
