ARCH2108 Animals, plants and people

1. ARCH2108Animals, plants and people Week 2 Animal genetics Taxonomy and nomenclature

2. The eukaryote cell

3. The nucleus contains chromosomes.Chromosomes can be arranged to form a Karyotype Human male karyotype

4. Total number of chromosomes is calleddiploid • But chromosomes are paired • The unpaired chromosome complement is called haploid • The diploid chromosome number is referred to as 2n • The human diploid number is given as • 2n = 46

5. Different species often have different karyotypesFour species of sheep Domestic sheep Ovis aries Esfahan mouflon Ovisorientalis 2n = 54 2n = 54 2n = 58 2n = 56 Tadjik urial Ovis vignei Argali Ovis ammon

6. Banded human karyotype

7. Some loci along human chromosome 7

8. What happens during formation of ova and sperm - 1 One diploid cell Two diploid cells

9. What happens during formation of ova and sperm - 2 Two diploid cells Four haploid cells

10. A pair of homologous chromosomes Dominant alleles Recessive alleles An eye-colour locus Blue-eyed allele Brown-eyed allele A blood-group locus A allele O allele

11. Homologous mutations • Because of the structure of DNA, the same mutations (mistakes in replication) recur independently in different individuals and in different species. (Homologous mutations). • These mutations are generally recessive. • Loci dealing with the same phenotypic character are often also arranged in an order of dominance.

12. Agouti (banded) hair Agouti Eumelanin Phaeomelanin Non-agouti

13. The Agouti locus: Agouti Abyssinian Aw B C D S Ta +Y

14. Interaction between the Agouti and Brown loci:Black agouti A B D C Ss T(+) +Y

15. The Brown locus:Non-agouti black aa B C D ss T? o (o or Y)

16. The Brown locus: Nonagouti brown aa bb C D ss T? O (o or Y)

17. The Chinchilla locus:Burmesesomewhat temperature-sensitive aa B cb cb D ss T? O (o or Y)

18. The Chinchilla locus: Siamesetemperature-sensitive aa B cscs D ss T? o (o or Y)

19. The Dilute locusDilute tabby (left) and dilute calico (right) aa B C d Ss T? Oo A B C d ss T(T or tb) o (or or Y)

20. The White Spotting locus aa B C D Ss T? Oo Homozygous Heterozygous aa B C D SS T? oo and oY

21. The Tabby locus Mackerel T(+) Abyssinian Ta Blotched Tb

22. The Orange sex-linked locus Heterozygote (female only) Calico or Tortoiseshell Homozygote Ginger aa B C D Ss T Oo ? ? C D ss Tbtb OY

23. The Mary Lyon effect(dosage compensation) • Females have two X chromosomes, males only one • One X is inactivated in each cell, so the sexes make equivalent amounts of X-chromosome gene product • Random X inactivation occurs in each cell early in foetal development • So the same active X chromosome is present in whole cell lines • Hence the patchwork effect in calico cats.

24. Other mutations(at different loci) Silver (loss of phaeomelanin) White Manx Cornish Rex (curly coated)

25. Homologous mutations in other felids White tiger cch Black leopard B (but recessive)

26. Taxonomy • Species – • A population (or series of populations) diagnosably* distinct from all others. • *with fixed heritable differences • *absolutely different • Often (not invariably) reproductively distinct. • Preferring not to breed with other species • Not, as a rule, subject to gene-flow from other species NOTE WELL: THERE IS NO REQUIREMENT THAT INTERSPECIFIC HYBRIDS ARE STERILE

27. Domestic species • Products of artificial (human) selection • Distinction from wild species may be arbitrary, artificial • Often more variable than wild species, both individually and between artificially-maintained breeds • Nevertheless it is convenient to regard them (or those that differ diagnosably from their wild representatives) as species distinct from wild forms

28. Binomial nomenclature • Each species’ name has two words: • Generic name • Always begins with a capital letter • Specific name • Always begins with a small letter Write them both in italics Example:Canis lupus – the Gray Wolf There are other species of the genus Canis, such as – Canis rufus – the Red Wolf Canis latrans – the Coyote Canis aureus – the Golden Jackal Canis mesomelas – the Black-backed Jackal

29. - And the domestic dog • Derived from Canis lupus, but we adopt the convenient fiction that it is a different species • Canis familiaris The manybreeds of dog are at least as different from each other as they are from the gray wolf, but we do not refer to them by different specific names. Feral dogs are sometimes given their own binomials, but there is no convention on this: Canis dingo – the Dingo Canis hallstromi – the New Guinea Singing Dog Canis tenggeranus– the Tengger Dog

30. A genus • Is a monophyletic* group of species • *derived from an common ancestor exclusive to them • with a particular time depth • Usually taken to be ± 6 million years

31. A family • Is a monophyletic group of genera • with a particular time depth • Usually taken to be ± 24 million years • Name ends in –idae • Name is not written in italics • Divisions within families are called subfamilies • Name ends in –inae • Divisions within subfamilies are called tribes • Name ends in -ini

32. An order • Is a monophyletic group of families • With a particular time-depth • - Usually taken to be ± 65 million years • - No standard ending • - Not written in italics • A class • A phylum • A kingdom

33. The Orders ofEutherianMammals *order has domestic representatives * * * * *

34. Perissodactyla and Artiodactylaboth are ungulates (hoofed)but feet are different Artiodactyla Perissodactyla

35. Carnivora Generally a Sagittal crest Carnassials (P4 and M1) Large canines

36. Rodentia and Lagomorpha Lagomorpha have a diminutive I2 Chisel-like incisors