The concept of niche overlap and competition is central to understanding how species interact within ecosystems. Competition occurs when two species vie for the same resources, leading to a reduced realized niche for one or both species.
Examples
-Sharks, Penguins and Dolphins
In all 3 lineages, natural selection favored adaptations that promote rapid swimming. They show superficial similarities in body structure.
development of phenotypic similarities between distantly related taxa
They just become more similar because of the environment acting on them
-Species cannot exchange genes; they don’t share the same genetic variation
Nothing to do with hybridization
Adaptative Radiation
development of a new species from a common ancestor due to adaptations to different environments
Character displacement
selection occurs in different directions
Has a zone of overlap, reducing competition not related to hybridization
As species converge toward each other some characteristics start to differ so there is less competition ex. Beak Size of similar bird species
Speciation is the evolutionary process by which new biological species arise.
Allopatric Geographical Speciation
4. reproductive isolation present without geographical barrier. speciation is complete
3. selection causes divergence in gene pools
2. gene flow interrupted variant types appear
1. two populations experience gene flow
Two models of allopatric speciation:
dumb-bell
peripheral
Exam I Topics
Inbreeding: Inbreeding is reproduction from the mating of parents who are closely related genetically
Inbreeding Depression
2. bringing together harmful genes related by decent
Subtopic
1. organisms are geared towards heterozygosity (good)
every generation of self-fertilization (“selfing”), heterozygous decreases by half
self-fertilization is the most extreme form of inbreeding
Gene Flow: (migration): movement of individuals between established, existing populations
equation to measure changes in allele frequency with immigration or emigration: q = M(qimm) + (1-M)(qoriginal)
M = migration rate
= migrant population / final population total
admixture: proportion of a genetic distance one population moves towards the other
1. level of admixture increases as populations genetically converge over generations
gene pool: allele frequency along all loci; gene frequencies will not revert back to original after migration
Genetic Drift
founder effect: loss of genetic variation when a new population is established by a small number of individuals from a larger population (chance deviation)
random changes in gene frequencies from one generation to another
Mutations are random changes in
genetic cod. Responsible for:
for men its age dependant
95% of all mutations are harmful
Generating new alleles
ultimate source of genetic variation
Exam III
Biological Control
reproductive control
release of sterile insects
use of chemical sterilants
release of incompatible pest strains
hormones
pheromones or behavioral chemicals
by other organisms
parasites, predators, pathogens
Niche Overlap And Competition
How species reduce competition
● when different species use the same resource they behaviorally reduce niche overlap to reduce competition
○ warbler example: each species of warbler spends most of its time in a designated area
barnacle example: the chthamalus has a fundamental niche greater than its realized niche because of competition with the balanus.
● In a graph plotted range diet vs range habitat of two species
a. as the overlap of the two species increases so does the level of competition, the
larger the range diet/range habitat -> more overlap -> more competition
he greater the similarity in requirements between two species, the greater the niche overlap
BIO 311D EC Map
I didnn't know how to indicate relationships between different exams by using the lines since this is a new software for me so I decided to type out the relationship of the ideas I have chosen. The three exam topics are related as they all factor in controlling population aspects especially size of the population. Exam One focused on how genetically populations are altered and controlled while Exam II focused on what happens when species interact. Lastly Exam III focused on specifically competition and how species must adapt in order to coexist. Basically the three exams show how the populations essentially alter contonously over time in order to keep up with the ever growing nature of biological species.
