Niches and adaptations

Lotic environment

running waters, rivers, and streams of freshwater

lentic

lakes, pinds, and wetlands of freshwater

limnology

The study of inland aquatic systems

aquatic zones

broad divisions in both ocean and other aquatic systems

pelagic zones

The middle and surface of the water vertically. Any space above the bottom.

benthic zones

the bottom of an aquatic environment

vertical zones in the ocean top to bottom

Epipelagic → mesopelagic → bathypelagic → abyssal → hadal zone

source of running water

rivers drain water from rain runoff and groundwater

horizontal zones in rivers from closest to farthest from water body

wetted channel → active channel → riparian zone

vertical zones in rivers from top to bottom

water column → benthic zone → hyporheic zone → phreatic zone

Hyporheic zone

where the surface meets groundwater in a river

• contains hyporheos which are adapted to high oxygen conditions but have a shorter lifespan

Phreatic zone

groundwater of rivers

• contains phreatobites which have longer lifespans than hyporheos

horizontal zones of stillwater

• limnetic zone is the open lake

• littoral zone is along the lake edge

vertical zones of stillwater from top to bottom

epilimnion → metalimnion → hypolimnion

thermal stratification

difference in temps can occur at the top and bottom of lakes and ponds

• summer and winter have separations of temp

• fall and spring have no difference in temp which allows the water to mix

bog

freshwater wetland from a source of rainwater

• water comes from acidic rain

fens

freshwater wetland from a source of groundwater

• ground provides a high concentration of minerals

niche

the range of abiotic and biotic interactions in which an organism can survive, grow and reproduce

fundamental niche

Abiotic conditions under which a species might live in the absence of interactions with other species

realized niche

environmental conditions under which a species might live when restricted by biotic interactions with other species

• a smaller subset from the fundamental niche

competitive exclusion principle

When two species occupy the same realized niche, one will always eventually outcompete and exclude the other

niche partitioning

Species in a community use the same limiting resources in different ways so that their realized niches are different and they can coexist.

phenotypic plasticity

the ability of a genotype to produce different phenotypes in response to distinct environmental conditions

heritability

h²

• the proportion of variation in a trait that can be determined by heritability

• ranges from 0 to 1

conditions to hardy weinberg equilibrium

• random mating

• no mutations

• large population size

• no immigration

• all genotypes have equal fitness

genetic drift

when a random event results in a large number of individuals being excluded from the population which results in less genetic variation

two types of genetic drift

• bottleneck effect

• founder effect

bottleneck effect

a reduction in diversity due to a large reduction in population size

founder effect

a reduction in diversity due to a subset of individuals leaving a larger population to colonize a new area

factors of natural selection

• more offspring are produced tan can survive

• traits vary among individuals within a population and may be heritable

• some heritable traits give individuals and advantage

• advantageous traits that provide higher fitness become more common

directional selection

when an extreme phenotype becomes more frequent

stabilizing selection

intermediate phenotypes increase in frequency, and extreme phenotypes decrease

disruptive selection

two or more extreme phenotypes become more frequent and the intermediate phenotype becomes less frequent

adaptive radiation

rapid evolution from one ancestor to a larger number of species

speciation

the process by which two or more species arise from a common ancestor

allopatric speciation

when a single population becomes spatially subdivided

parapatric speciation

occurs when a population is distant enough that it does not mate randomly

• example: snails dont move fast enough to mate with one too far away

sympatric speciation

occurs when a populations interbreeding fails due to nonspatial isolating mechanisms, such as positive assortative mating