Diversity Flashcards
What is conservation biology?
An integrated, multidisciplnary scientific field that has developed in response to the challenge of preserving species and ecosystems
What are the three aims of conservation biology?
- To document full range of biodiversity on earth
- To investigate human impact
- Approach extinction prevention, resotre communities
What is biodiversity?
“The variety of life, encompasses all forms, levels, and combinations of natural variaiton, at all levels of biological organization”
What are the three levels of biodiversity?
- Ecological
- Genetic
- Organismal
Biological species definition
A group of individuals that can potentially breed among themselves in the wild and do not breed with individuals of other groups
Morphological Species definition
Group of individuals that appear different from others, are morphologically distinct
What is evolutionary species definition?
Group of individuals that share unique similarities in their DNA and hence their evolutionary past
What is species richness
The number of unique species in a collection or set of observations
What are 3 reasons species richness estimates may be innacurate?
- Inventories are incomplete
- Described species tend to be larger bodied, more abundant, and more widespread
- Distributions are best known for temperate regions
Heterogenous biodiversity distribution meaning
Biodiversity is distributed ‘unevenly’
Some areas are largely devoid of life whilst others are hyperdiverse
desert vs. rainforest
What is a biodiversity hotspot?
Areas with an exceptionally high concnetration of endemic species and are undergoing exceptional loss of habitat
What are the two strict criteria to qualify as a biodiversity hotspot?
- Contain at least 1500 species of endemic vascular plants
- have lost at least 70% of its primary native vegetation
What is the latitudinal gradient in species richness?
Species richness peaks at the equator
What is the species-energy relationship?
The amount of available energy in an area impact levels of diversity
How are evapotranspiration and potential evapotranspiration used in the species-energy hypothesis?
- Evapotranspiration measures the simultaneous availablility of water and solar energy
- potential evapotranspiration reflects the energy available to evaporate water to the atmosphere
What is the productivity hypothesis?
Energy constrains richness via trophic cascades
(Richness is limited by available energy)
What is the ambient energy hypothesis?
Solar energy impacts organisms and diversity through their physiological response to temperature
- more costly to live at higher latitudes (out of thermal neutral zone)
Is water or water energy the primary predictor of plant richness?
In tropical areas - water variables are best predictors
In cool areas, water energy variable are best predictors
Is water or energy the primary predictor of vertebrate richness?
In warm areas water is most associated with richness
In cold climates, ambient energy is most associated
What were the two largest mass extinctions?
The Cretaceous (dinosaurs) and the Permian (50% of animals)
Where are the highest extinction rates and why?
On islands (flightless birds)
- Small populations and low dispersal
Why are freshwaters imporant
They hose 1/4 of vertebrate diversity while they only cover a small portion of the Earth’s surface
What is the current estimated extinction rate vs the background extinction rate?
0.1-1 E/MSY (background)
vs
1 E/MSY (current)
What is a global hectare?
A biologically productive hectare with world average biological productivity for a given year
Biocapacity
Area of productive land available to produce resourves or absorb carbon dioxide waste, given current management practice
What is the available biocapacity per person on our planet?
1.7 global hectares
What are the 5 main pressures on biodiversity
- Habitat loss and degradation
- Climate change
- Pollution and nutrient loading
- Overexploitation and unsustainable use
- Invasive species
Habitat fragmentation 3 effects on land area
- Habitat fragments differ from original habitat
- Fragments have a greater amout of edge for area
- Centre of each habitat fragment is closer to an edge
Why is larger edge due to habitat fragmentation bad?
- Microenvironment at edge is different from interior
- Edge is disturbed habitat
- Brings wild populations in contact with domestic plants and animals
What are three effects of habitat fragmentation on populations?
- Limit potential for dispersal and colonization
- Reduce foraging ability
- Precipitates population decline by dividing up existing population
What is extinction debt?
The future extinction of species due to events in the past (time lag)
Explain species area curves
There is often a positive relationship between area and the number of species
- slope is steeper in fragmented landscapes due to greater species lost
Eutrophication
Human sewage and fertilizers release large amounts of nitrates and phosphates into freshwater systems
Leads to eutrophication
Leads to hypoxia
Overexploitation
When harvest rate of any population exceeds its natural replacement rate, through reproduction or immigration
What are the “missing fish”
FAO data of fish exploitation is probably underestimated due to artisanal and subsistence fisheries, bycatch, illegal and unreported catch
What is the fishing down process
Successive loss of the largest individuals and species in favor of smaller, faster, and shorter-lived fish
The bushmeat crisis
Populations of large primates, ungulates, and other mammals may be reduced by 80% or more - “half-empty forest”
How does habitat loss effect community dynamics?
- Some plants rely on dispersal by species
- Control by grazing
- Disrupt nitrogen cycling
- Reduced competition
- Habitat engineers
