FOUR LIMITS TO ADAPTATION

1
IMPERFECTION GUARANTEED Mutation very rare
Selection often slow - constrained
by genetics e.g.
Sickle Cell Anaemia -
constrained by history
e.g. Pandas thumb Drift often
eliminates new alleles Gene flow can
over-ride selection
2
LECTURE 12WHAT IF ANYTHING ARESPECIES?
Real or human imaginings?
3
(No Transcript)
4
(No Transcript)
5
GREAT TIT
Parus major
Genus name in italics capitalised
6
GREAT TIT
Parus major
species name in italics lower case
7
A SPECIES IS PART OF A GENUS
8
A GENUS IS A GROUP OF SIMILAR SPECIES
1 genus? 2 genera? 3
genera?
9
A FAMILY IS A GROUP OF SIMILAR GENERA
TIT FAMILY
10
AN ORDER IS A GROUP OF SIMILAR FAMILIES
SONGBIRD ORDER
11
NO AGREEDDEFINITION OFSPECIES
Two most common ones Morphological species
concept Reproductive species concept Many
others but all have flaws
12
TRANSFORMISM
Buffons view
Lion
Cat kind
Leopard
Tiger
Speciation occurs
13
MORPHOLOGICAL SPECIES CONCEPT
Traditional view Members of same species look
alike Basis of field guides
14
MORPHOLOGICAL SPECIES CONCEPT

HAS MANY PROBLEMS Here are just five
15
1. Age differences
16
2. Sex differences
male female
17
Sex differences in Angler Fish
male female
18
Sex differences in Angler Fish
males female
19
3. Ecological morphs
Plankton-feeding
Mexican fish Ilyodon
20
4. Sibling species
Marsh Tit
Willow Tit
Distinguished 1897
21
5. Logic?
Why should species have to look different?
22
Mixture of Neisseria gonorrhaoeae N.
meningitidis
23
MORPHOLOGICAL SPECIES CONCEPT
Problems age differences sex
differences ecological morphs sibling
species logic no causal link
24
REPRODUCTIVE SPECIES CONCEPT
Members of same species can interbreed Members
of different ones cannot
Ernst Mayr cunningly renamed this idea
25
BIOLOGICAL SPECIES CONCEPT
Ernst Mayrs cunning name for Reproductive
Species Concept
26
BIOLOGICAL SPECIES CONCEPT

HAS MANY PROBLEMS Here are just five
27
Some organisms do not mate
1. Asexuals 2. Fossils
Neisseria
28
3. Others rarely mate
Some bamboos - roughly every century
29
4. Vast number of tests needed49 million needed
for birds alone
30
5. Logic?
Hybrids occur
31
HYBRIDS SECTION A EXAMPLES
32
HYBRIDS BETWEEN SPECIES IN SAME GENUS (1)
Panthera CATS
33
LION LEOPARD TIGER
34
MAKING A TIGON
35
MALE FEMALE TIGONS
36
MAKING A LIGER
37
LIGERS MALE FEMALE
38
MALE FEMALE
LEOPON LIOPARD
39
HYBRIDS BETWEEN SPECIES IN SAME GENUS (2) Ursus
BEARS
40
POLAR BEAR Ursus maritimus
41
GRIZZLY BEAR Ursus arctos
42
PIZZLY BEAR b. 1876
43
GROLAR BEAR d. 2006
44
HYBRIDS BETWEEN SPECIES IN DIFFERENT GENERA (1)
ORCHID FAMILY
45
CHERRY SPIDER ORCHID
PINK FAIRY ORCHID
46
HYBRIDS BETWEEN SPECIES IN DIFFERENT GENERA (2)
TYPICAL SNAKE FAMILY (Colubridae)
47
JUNGLE CORNKing Snake x Corn Snake
48
HYBRIDS BETWEEN SPECIES IN DIFFERENT
FAMILIES GAMEBIRD ORDER
49
PEACOCK
GUINEA-FOWL
50
PEA-GUINEAS
51
HYBRIDS SECTION B THREE CONSEQUENCES
52
CONSEQUENCE 1 HYBRID SWARMS
53
RED CAMPION WHITE CAMPION
Fertile hybrid
54
CONSEQUENCE 2 CONSERVATION PROBLEMS
55
CONSEQUENCE 3 NEW SPECIES