EVOLUTION (BIOL 318) BIOLOGY
EXAM 3 STUDY NOTES (I studied before
my exam) COMPETE AND ACCURATE
LATEST GUIDE VIRGINIA
COMMONWEALTH UNIVERSITY
, Introduction to Sexual Reproduction and Costs of Sex:
● Types of Reproduction:
○ 2 broad types:
■ asexual: production of offspring from unfertilized gametes
● apomixis: gamete undergoes a "mitosis-like" cell division.
Each daughter cell has an unreduced number of chromosomes
(=apogamy in plants)
● Automixis: meiosis occurs, but diploidy is restored by fusion of melotic products
■ Sexual: offspring develop from fusion of gametes from different
individuals
● Amphimixis
○ Meiosis in separate individuals and gamete fusion (syngamy either within one individual
or externally
3 steps:
● recombination
● gamete production
● gamete fusion
Types of Automixis:
● Gamete duplication
○ Offspring form by replication of haploid genome
○ Meiosis proceeds completely and a single sister chromatid is duplicated
● Terminal Fusion:
○ Offspring formed from meiotic products containing sister chromatids fuse
○ Meiosis proceeds completely and two sister chromatids are joined
● Central fusion:
○ Offspring form when meiotic products containing homologous chromatids fuse
○ Meiosis proceeds completely and two homologous chromatids are joined
● Gamete Size:
○ Sexual reproduction involves the fusion of gametes from two parents
○ Across multicellular life, gametes typically differ in size between parental types
■ Why?
■ How?
○ Unequal size gametes is known as Anisogamy!
■ Evolution of anisogamy:
● Based on population that produces gametes of various sizes
● Trade offs:
○ Inverse relationship b/w gamete production and gamete size
○ Inverse relationship b/w gamete mobility and gamete size
○ Positive relationship b/w gamete size and zygote survival
● Why sex?
○ 3 common hypothesis:
■ Environmental unpredictability
■ Number of niches
■ Parasite load
● When high>favor sexual
● When low>favor asexual
● Cost Benefit Analysis of Sex:
○ Sexual reproduction is seen in most multicellular euk
■ Why?
EXAM 3 STUDY NOTES (I studied before
my exam) COMPETE AND ACCURATE
LATEST GUIDE VIRGINIA
COMMONWEALTH UNIVERSITY
, Introduction to Sexual Reproduction and Costs of Sex:
● Types of Reproduction:
○ 2 broad types:
■ asexual: production of offspring from unfertilized gametes
● apomixis: gamete undergoes a "mitosis-like" cell division.
Each daughter cell has an unreduced number of chromosomes
(=apogamy in plants)
● Automixis: meiosis occurs, but diploidy is restored by fusion of melotic products
■ Sexual: offspring develop from fusion of gametes from different
individuals
● Amphimixis
○ Meiosis in separate individuals and gamete fusion (syngamy either within one individual
or externally
3 steps:
● recombination
● gamete production
● gamete fusion
Types of Automixis:
● Gamete duplication
○ Offspring form by replication of haploid genome
○ Meiosis proceeds completely and a single sister chromatid is duplicated
● Terminal Fusion:
○ Offspring formed from meiotic products containing sister chromatids fuse
○ Meiosis proceeds completely and two sister chromatids are joined
● Central fusion:
○ Offspring form when meiotic products containing homologous chromatids fuse
○ Meiosis proceeds completely and two homologous chromatids are joined
● Gamete Size:
○ Sexual reproduction involves the fusion of gametes from two parents
○ Across multicellular life, gametes typically differ in size between parental types
■ Why?
■ How?
○ Unequal size gametes is known as Anisogamy!
■ Evolution of anisogamy:
● Based on population that produces gametes of various sizes
● Trade offs:
○ Inverse relationship b/w gamete production and gamete size
○ Inverse relationship b/w gamete mobility and gamete size
○ Positive relationship b/w gamete size and zygote survival
● Why sex?
○ 3 common hypothesis:
■ Environmental unpredictability
■ Number of niches
■ Parasite load
● When high>favor sexual
● When low>favor asexual
● Cost Benefit Analysis of Sex:
○ Sexual reproduction is seen in most multicellular euk
■ Why?
