Transcript Defining species

Conservation biology challenges
Global warming
Habitat destruction
Extinctions (loss of biodiversity)
Overexploitation (harvest)
Exotic species
loss of genetic diversity
What is the basic unit of conservation?
(what are we trying to conserve?)
Levels of genetic diversity
ATTGACTTAAGCGTAG
TAACTGAATTCGCATC
loci
chromosomes
individuals
populations
species
What is a species?
What is a species?
X
lake trout
(Salvelinus namaycush)
=
splake
brook trout
(Salvelinus fontinalis)
What is a species?
X
lake trout
(Salvelinus namaycush)
brook trout
(Salvelinus fontinalis)
=
X
splake
lake trout
=
‘backcross’
Problems with defining/differentiating species
What do these plants
have in common?
cabbage, broccoli, Brussels sprouts,
cauliflower, collard greens, kohlrabi
they are all Brassica oleraceae
Problems with defining/differentiating species
for conservation
easy example: geographic separation…
Eurasian yellow perch (Perca fluviatilis)
Yellow perch (Perca flavescens)
more challenging – sympatric groups
Smelt (Osmerus mordax) – normal race
Smelt (Osmerus mordax) – giant race
Problems with defining/differentiating species
• cryptic species (look the same, actually different)
grey tree frog
Hyla versicolor (4N)
Hyla chrysoscelis (2N)
Problems with defining/differentiating species
• cryptic species
• morphological differences (look different, actually the same)
– phenotypic plasticity
zebra mussel (Dreissena polymorpha)
quagga mussel (Dreissena bugensis)
Are these fish in the same family? Genus? Species? How do you know?
Problems with defining/differentiating species
• cryptic species
• morphological differences
• life history differences within species
Freshwater, landlocked
rainbow trout (Oncorhynchus mykiss)
Marine, anadromous
steelhead trout (Oncorhynchus mykiss)
Problems with defining/differentiating species
• cryptic species
• morphological differences
• life history differences
• taxonomic decisions - lumpers vs. splitters
Lampsilis cardium
(pocketbook mussel)
Lampsilis ovata
(pocketbook mussel)
Problems of incorrect taxonomic classification
• Endangered species may not be recognized, protected
(tiger, tuatara)
• Resources may be wasted by conserving common species,
or hybrids (red wolf)
• Genetic pollution due to incorrect transplantation or
augmentation of populations (ibex)
• Resources for improving fitness of inbred populations may
be missed (dusky seaside sparrow)
(credit to K. Dasmahapartra)
Evolutionary Unit (EU) ~ Evolutionarily significant
unit (ESU) (Waples 1991):
population of organisms that is considered distinct for
purposes of conservation
“a group of organisms that represents a segment of
biological diversity that shares evolutionary lineage
and contains the potential for a unique evolutionary
future.”
Defining evolutionarily significant units:
•
•
•
Current geographic separation,
or
Genetic differentiation at neutral markers among related
ESUs caused by past restriction of gene flow,
or
Locally adapted phenotypic traits caused by differences in
selection.
Why genetics???
Taxonomic identification and errors
Importance of genetic diversity for evolutionary potential
Population fragmentation and loss of gene flow
Issues of small population size (inbreeding, drift)
Captive population management (selection, reintroduction)
Forensics