Topic 13 Biodiversity and Conservation

Genetic diversity

the total genetic information of all individuals.

small population sizes can lead to inbreeding and genetic drift

Extinction risk increases with reduced genetic diversity

Species diversity

the number of species in an area.

Ecosystem diversity

the variety of biotic components in communities in a region, along with abiotic components like soil, water, and nutrients

Ecosystem Functions

The biological and chemical processes of ecosystems, like primary production, nutrient cycling, carbon storage

Ecosystem Services

The direct and indirect contributions of biodiversity to human survival and quality of life

Species diversity can be measured in different ways

Species richness

Species diversity

Phylogenetic diversity

Functional diversity

Species richness

A count of the number of species in an area

Species diversity

includes both species richness and the relative abundance of those species

Phylogenetic diversity

Evolutionary distinctiveness. Measures branch lengths in a phylogeny.

Functional diversity

Ecological distinctiveness. Count and categorize functional traits of species.

Endemic species

Species found in one area and nowhere else on earth

Species richness varies across the planet

Latitudinal Gradient in Species Richness

The climate in the tropics likely contributes to higher speciation and lower extinction for most species groups

BC is the most biodiverse province in Canada, why?

Topography quite variable → rainshadow effect

Mountainous regions tend to have exceptionally high diversity: different species at different elevations

the only desert in Canada

Species richness tends to scale with area

Island biogeography theory predicts species richness as a function of island size and distance from the mainland

Small islands: low immigration and high extinction rates relative to large islands.

Near islands: higher imigration and lower extinction rates relative to remote islands

It’s easier for organisms to disperse to the island, and populations can be rescued by ongoing immigration

Biodiversity can increase the ability of a community to resist or recover from disturbance

Resistance: How well a community resists change in the face of a disturbance

Resilience: How quickly a community recovers following a disturbance

Communities with higher species richness tend to be more resistant and resilient

How has biodiversity on earth changed over time?

Since the Cambrian explosion, biodiversity has generally

increased, except when there were mass extinctions.

Background Extinction

Ongoing loss of species, due to changes in abiotic and biotic environment

normal, gradual rate at which species go extinct over time, excluding major extinction event

Mass Extinction

When > 60% of species alive go extinct within ~ 1 million years

There have been five mass extinction events in the history of earth

End-Ordovician: bout 85 % of species. Massive glaciation lowered sea levels (all life was in the sea)

Late Devonian: 75% species loss, likely due to depletion of O2 in the ocean from rapid algae growth

End-Permian: 96% of species (on land and in the oceans) due to massive volcanic activity

End-Triassic: 80% species loss, also due to volcanic activity

Cretaceous: 75% of species including non-avian dinosaurs, due to asteroid impact and volcanism

Habitat loss

the main reason species are threatened with extinction, globally

Conservation Biology

The effort to study, preserve, and restore diversity

How do we decide which areas to conserve?

We can use ideas from Island Biogeography for conservation planning

• Large reserves are better than small

• Proximity to other reserves is good (similar to islands near mainland)

• Corridors that connect habitat fragments can aid conservation

Habitat loss can be countered by habitat creation

Agriculture often causes habitat loss and degradation, but many crops need pollinators (like blueberries!)

Wildflower meadows planted near crops provide habitat for pollinators, which also increases crop pollination (and profit for farmers)

Ecological Restoration addresses habitat degradation

Invasive Species

A non-native species that, once introduced to a new area, causes ecological or economic harm.

• High competitive ability

• High reproductive output

• Few natural enemies in their introduced range

• A broad niche (can live in many environments)

Invasive species pathways, and costs

While many invasive species are accidentally introduced, some are introduced deliberately (especially plants)

Invasive species are costly, especially for agriculture. The most costly invasives are insects and mammals.

Invasive species management plans can slow or reverse spread

Overexploitation

Unsustainable removal of wildlife from the natural environment, for use by humans

Main threat for marine species

Government regulation can preserve both fish populations and the livelihood of fishing communities

Poaching

Collectors

The pet trade

Pollution

The release of chemicals and waste into ecosystems; can change biotic and abiotic conditions

• Industrial pollutants

• Pharmaceuticals

• Pesticides

• Herbicides

• Nutrients (N, P)

• Garbage/Plastics