Biodiversity L2

Biological species concept

A group of

organisms that can interbreed and produce

fertile offspring (Mayr)

Morphological species concept:

Organisms

are grouped by appearance or physiology

Phylogenetic species concept:

Organisms

with a shared evolutionary lineage that can be

differentiated from others based on a

common trait or gene

What is the species richness of the

community below?

5

180+(180-100)+100+(100-90)+90+90 = 550

how many species should go extinct per year assuming 5 million species on earth. 1- 10 million years of persistence

1/1 million years * 5 million species = 5 species per year

1/10 million years * 5 million species = 0.5 species per year

overkill hypothesis

humans could be responsible for pleistocene extinctions across the world - human arrival correlates w/ dramatic wildlife declines esp in size (megafauna)

4 notable modern extinctions

1. thylacine (dog/zebra)

2. passenger pigeon

3. lyalls wren

4. golden toad

what traits do vulnerable species share

1. large body size

2. small range size

3. small pop size

4. habitat or diet specialist

species area approach

more habitat = more species

S=CA^Z

s = number of species

a = area of the land form

c and z are constants

c= 1

z= 0.25

find s for species area approach when A=10

s = 1×10^0.25 = 1.8

why do larger areas have more S

s = number of species

More resources, varying environment & niches, separation of environments (speciation) 

extinction debt

predicted eventual loss of unviable populations

name two problems with Species area approach

1. extinctino may be slower than habitat restoration

2. species can often persist once habitats are converted (farms)