12. Mating Flashcards
4 methods of asexual reproduction
-Binary fission
-Fragmentation
-Parthenogenesis
-Runners
Sexual selection
Mate choice by one sex and/or competition for mates among individuals of the same sex
May result in selection for certain traits
What are the 3 sex types
-Male
-Female
-Hermaphrodite
What are the 2 types of hermaphrodite
- Instantaneous- can perform male and female functions at the same time
- Sequential- individual changes sex over time
What are the 2 types of sequential hermaphrodites?
- Protandrous (male becomes female)
- Protogynous (female becomes male)
What are the male and female plant sex organs?
Male:
Stamen (anther and filament)
Female:
Pistil (stigma, style, ovary)
Can all plants self pollinate?
No
75% are hermaphroditic, but some have evolved methods to prevent self pollination
Manogamy
A mating system with one male and one female that have an exclusive relationship for some period of time
What are the types of monogamy?
- Genetic monogomy: parents raise their genetic offspring (full fidelity)
- Social monogamy: parents raise young that may or may not be their genetic offspring
Why might monogamy have evolved?
- Ansiogamy: females are more selective since their gametes are larger, finite, and more energetically costly
- Parters are rare or have wide territories
- Parental care means higher fitness of offspring
Promiscuity
A mating system where individuals have several sexual partners
3 types of promiscuity
- Polygyny- 1 male, many females
- Polyandry- 1 female, many males
- Polygynandry- many males & females
Secondary sex characteristics
Characteristics of males and females not directly involved in reproduction
Sexual dimorphism
When a species has several secondary sex characteristics that differ between males and females
Intersexual
Selection for traits that increase chances of being chosen by the opposite sex
e.g. peafowl, robins, etc
Intrasexual selection
Selection for traits that provide an advantage during competition among the same sex for access to mates
e.g. deer antlers, beetle horns
What are the disadvantages for some secondary sex characteristics?
- Increased mortality in fights (antlers)
- Increased predation (loss of camouflage)
- Higher allocation of resources at the expense of other functions
- Habitat compatibility
Describe the study on guppies and the tradeoff between predation pressure and sexual selection
-Female guppies are less colourful than males
- Females mate with more colourful males
-3 treatments (high, low, and no predation)
-Guppies in low/no predation environments have more spots
-Guppies in high predation environment have less spots
-when guppies are transferred from high to low predation, future generations evolve more spots
What causes non random mating in plants?
- Competition between pollen from different donors
- Interference competition- interactions between pollen inhibits germination
Sexual conflict
Asymmetry between sexes in potential evolutionary benefits/costs from mating
e.g. being pregnant and caring for young for a female is costly and relatively inexpensive for males
Coevolution
Reciprocal evolutionary interaction between 2 or more evolving groups
