envs157 - lecture 1 biodiversity

ecology scales

time, spatial, biological

biological hierarchy

cells>tissues>organs>individual organisms>populations>communities>ecosystems>ecoregions>biogeographic regions>biosphere

biodiversity

variation of life at all levels of biological organisation

what levels can biodiversity be measured at

genetic, species, generic, ecosystems, functional, phylogenetic

what is the problem with measuring biodiversity

it is a multifaceted concept with no single method for measuring it

species estimates

2 billion living species

how many insects? and what about them

approx 6.8 million. they can host at least ten unique bacterial species

how have the species estimates changes through time

1992 - 72% animals

2011 - 90% animals

2017 - 78% bacteria

biomass estimates _____

marine arthropods dominate,

alpha diversity

locally measured - one site.

number of species within a given area

identity of species matters

beta diversity

measured between two sites

high beta diversity implies low similarity in species composition among sites

gamma diversity

total species diversity in a landscape

combination of alpha and beta diversity

evenness

difference in abundance need considering

what are rarefaction curves

indicate the completeness of sampling

can extrapolate to estimate number of species in a particular area

steep curve - inadequate sampling

rarity factors

size of geographic range

habitat specificity

local population density

what affects patterns of diversity

latitude

elevation

temperature and climate

biodiversity hotspot

a biogeographic region with significant levels of biodiversity that is threatened with destruction

how many biodiversity hotspots are there

36

what qualifies as a hotspot

contain at least 1500 species of endemic vascular plants

have lost at least 70% of its primary native vegetation

hot spot examples

sundaland - south east asia

more than 15000 endemic plant species, 95% vegetation loss

cerrado - brazil

more than 10,000 plant species, 80% vegetation loss

species

a group of similar organisms whose members freely interbreed

population -

a group of organisms of the same species that occupy and live in the same area at the same time

community

all the populations of different species that live and interact in the same area at the same time

ecosystem

a community and its physical -abiotic- environment

landscape

several interacting ecosystems

ecology

the study of the distribution and abundance of organisms and the interaction among these that determines their distribution and abundance (Townsend et al 2008)

keystone species

disproportionately large effect on its environment relative to its abundance