Mating system

• Monogamous

• Polygamous

-Polygyny

-Poly androus

-Random (promiscuous)

Behavioral polymorphism

Ultimate goal of sexual reproduction?

If Dr. Kim married to Jiwoo ChoiSexual reproduction: The fusion theory

Fusion

If Dr. Kim married to Jiwoo Choi

Recombinants of traits

Sexual reproduction: The particulate theory

Natural selection and

Genetic Polymorphism

Mechanism of Natural selection

Natural selection and genetic

polymorphism

Negative selection

no selection

Positive selection

Time

Natural selection rates:

KA/KS ( dN/dS)

• KA/KS << 1 purifying selection

• KA/KS = 1 neutral evolution

• KA/KS > 1 positive diversifying selection

0.0 1.0

← conserving

Negative selection,

constraint

Diversifying →

Positive selection

• Compares sequence changes under selection with the background rate

• A measure of selection pressure averaged across the entire gene

• KA (dN) the number of nonsynonymous substitution (a.a changing)

• KS (dS) the number of synonymous substitution (a.a conserving)

Ka/KS

http://www.bioinfo.no/tools/kaks

Face-shape convergence

Time

Diversifying or conserving? Using the genetic code table, calculate Ka/Ks for the following alignment:

(http://www.megasoftware.net)

(http:// abacus.gene.ucl.ac.uk/software/paml.html)

D. melanogaster TTT TCT CAT

D. simulans TTC TCC CGT

SEMG2 Evolution

SEMENOGELIN II• Gene involved in sperm motility

• Potential role in competition among males in promiscuous primate

societies

Male Females

Polyandrous Monoandrous

Lineage-specific Ka/Ks values of

SEMG2 in primates

Rate of molecular evolution of the seminal protein gene

SEMG2 correlates with levels of female promiscuity

So, what is your interpretation on the

correlation between SEMG2 and behavior?

# male partner testis size coagulating rate

dN/dS

Sliding window analysis SEMG2

Genetic factor and Brain size

Evolution of Nervous System Genes

• Evolution of Nervous System Genes and Housekeeping Genes in Primates and Rodents(A) Evolutionary rates in primates and rodents.(B) Percentage of genes that evolved with higher Ka/Ks in one or the other mammalian order.The p values indicate the statistical significance of primate-rodent d

Ka/Ks Distributions of Nervous System Genes

• The Ka/Ks Distributions of Nervous System Genes and Housekeeping Genes in Primates and Rodents(A) Nervous system-related genes.(B) Housekeeping genes.The p values indicate the statistical significance of primate-

rodent disparities.

Nervous system genes showing faster

evolution in primates

Microcephalin and ASPM (abnormal spindle-like, microcephaly associated gene)

Spindle shape

Evolution of the human brain -

divergence

• Studies show two genes linked to brain size are rapidly evolving in humans

• Growth of brain size and complexity is likely still going on

• Accelerated evolution in humans among numerous

genes, including microcephalin and ASPM(abnormal spindle-like microcephaly-associated). Both of these genes regulate brain size and “were good candidates to look for signatures of selection”

Evolution of the human brain -

polymorphism

• Variations of microcephalin and ASPM within modern humans

• For microcephalin, the new variant class emerged about 37,000 years ago and now shows up in about 70 percent of present-day humans.

• For ASPM, the new variant class arose about 5,800 years ago and now shows up in approximately 30 percent of today‟s humans

• Very intense selection pressure that drove up their frequencies in a very brief period of time

Fast evolution coincides with modern

human historical events

• Microcephalin variant appears along with the emergence of such traits as art and music, religious practices and sophisticated tool-making techniques, which date back to about 50,000 years ago.

• The ASPM variant coincides with the oldest-known civilization, Mesopotamia, which dates back to 7000 BC.

The ASPM, asp (abnormal spindle)-like, microcephaly associated gene

Isoleucine-Glutamine repeats

If you compare the # of IQ repeats

among HUMAN, MOUSE,FLY, WORM…

ASPM determine brain size

HUMAN 74

MOUSE 61

FLY 24

WORM 2

Isoleucine-Glutamine repeats

Microcephalin and ASPM

polymorphism • Variation frequency of the two genes, the researchers

surveyed more than 1,000 individuals, representing 59 ethnic populations worldwide.

• For each gene, the scientists identified a large number of haplotypes, or variant copies. They found that one class

of haplotypes, called haplogroup D, shows two distinct characteristics.

• First, they are very young. Second, despite recent

emergence they have spread rapidly.

Investigate whether positive selection has

continued to operate on ASPM since the

emergence of anatomically modern humans

Implications - IQ?

• A series of studies suggest that there is

some correlation between brain size and

intelligence, but with some exceptions.

Although, on average, a man‟s brain is 3

to 4 percent larger than a woman‟s, both

sexes score similarly on IQ tests.

Ongoing Adaptive Evolution of ASPM, a Brain

Size Determinant in Homo sapiens

• Homozygous null mutations of ASPM cause primary microcephaly

• Phylogenetic analysis of ASPM has revealed strong positive selection in

the primate lineage leading to Homo sapiens, especially in the past 6 million years

of hominid evolution in which ASPM acquired about one advantageous

amino acid change every 350,000 years.

Size of brain increase

Fast evolution of a „speech gene‟ -

divergence in FoxP2

In 75 million years since the divergence of mouse and chimpanzee lineages

only one nonsynonymous change has occurred in FOXP2. But in only six

million years since the divergence of man and chimpanzee lineages two

nonsynonymous changes have occurred in the human lineage

Silent and replacement

nucleotide substitutions

mapped on a phylogeny of

primates. Bars represent

nucleotide changes. Grey

bars indicate amino-acid

changes

Fast evolution of a „speech gene‟ -

polymorphism in FoxP2

By looking at silent polymorphisms in the gene, Enard et

al estimate that the mutations in the FOXP2 in the human

lineage occurred between 10,000 and 100,000 years ago.

Strong evidence of a selective sweep that was caused by

one or both of the mutations in humans, and then they go

on to speculate that this change has been critical in the

evolution of human speech, perhaps by enabling fine oro-

facial movements essential to speech

Divergence and Convergence of gene

sequences could the mechanism of

molecular evolution…

Conclusion

Believe or not….^^