Marine Ecology and Populations Flashcards
Divergent Evolution
One species diverges (divides) into new species
Allopatric Speciation
- Type of divergent evolution
- Geographic speciation: biological populations become geographically isolated from each other in a way that prevents / interferes with gene flow
Peripatric Speciation
- Type of allopatric speciation
- Mode of speciation in which a new species is formed from an isolated population
Convergent Evolution
Species which are unrelated to one another but live in similar environments may independently acquire similar traits (ex: dorsal fins on sharks and dolphins)
Adaptation
The process of gaining traits that lead to better reproductive success
Evolution
The creation of a new species by way if adaptations and natural selection
How do populations grow?
Exponentially
Carrying capacity (k)
The largest population size that can be sustained by the available resources
Can exponential growth continue forever?
No!
- A carrying capacity is reached
- Limiting factors determine carrying capacity
What is the population growth trend known as?
Logistic growth: populations grow exponentially until a carrying capacity is reached
What kinds of resources can act as limits?
Any resource important to the survival of a species (ex: sunlight, water, food etc.)
Intraspecific Competition
Members of the same species competing for resources
Interspecific Competition
Member of different species competing for resources
Will intraspecific competition affect larger or smaller populations?
- Larger
- If a population is under its carrying capacity (lots of resources) competition may not occur
What is the competitive exclusion principle?
- Complete competitors cannot coexist in the same place (there will aways be a winner!!)
- If two species have identical needs for resources there will be extinction / niche differentiation
Ecological Niches
A species unique requirements and adaptations for survival
Fundamental Niche
Entire set of conditions under which an animal can survive and reproduce
Realized Niche
Set of conditions actually used by a given animal after interactions (completion) with other species have been taken into account
Barnacle Example
Functional Redundancy
Multiple (very different) species can share an ecological role
Why is functional redundancy a problem?
- It implies that species loss = compensated
If you consider multiple dimensions of function there may not be as much redundancy between organisms
What factors influence the effects of species loss?
- The variety of functions and diversity of species within a functional group
- How functions are spread put across different groups of species
- Whether other species in the same group can compensate for the loss of one species’s function (functional redundancy)
Keystone Species
Organisms that help hold the system together (even if other species are able to fill their role)
Low abundance or biomass of this species will influence the structure and function of ecosystems
How do predator keystone species influence communities?
They can exert pressures on lower trophic levels to prevent them from monopolizing certain resources
How do mutualistic keystone species influence communities?
Species that support the life cycle of a variety of species within a community (ex: pollinators)