Prep101: Cycle 7 Flashcards
What is sex?
Recombination of genes
What are the main factors in the huge source of variation in sexual reproduction?
- Random mating (combining genetics from two organisms)
- Random segregation of parental chromosomes in meiosis metaphase I and II
- Meiotic recombination between homologous chromatids or “crossing over” at prophase I
True or False:
Sex is not the only method of reproduction
Explain
True, many organisms reproduce asexually
E.x. Female asexual lizards that still exhibit vestigial mating behavior
Define:
Asexual reproduction
Produce exact copy of self, no genetic exchange of information
What are the benefits of sexual recombination for the population?
- Speeds up evolution
- Discads harmful mutations and creates beneficial mutations
- Decreases likelihood of extinction
List the:
Benefits of asexual reproduction
- No time spent to find a mate (faster generation time)
- No loss of genetic information passed to offspring (100% of your genome is transmitted to next generation)
List and explain the:
Problems of asexual reproduction
- Cannot combine beneficial mutations. Each individual would need to randomly mutate and accumulate these within one lineage, results in slower evolution for adaptive traits combining to increase fitness of the organisms
- Cannot “lose” deleterious/harmful mutations. This is because 100% of the DNA is transmitted to the next generations
List and define:
Examples of asexual reproduction in plants
- Rhizomes: Modified underground stems that can produce new roots and shoots
- Adventitious roots: Non-root tissue transofrms into root tissue
- Tubers: Underground swollen root that acts as storage organs that can sprout new plants
- Bulbs: Underground lateral buds producing new plants
Give an example of a(n):
Rhizome
Strawberry plants
Give an example of a(n):
Adventitious roots
Strawberry plants
Give an example of a(n):
Tubers
Potatoes
Give an example of a(n):
Bulbs
Onions
List and define examples of:
Asexual reproduction in animals
- Fragmentation: Intentionally extend OR excise part of animal and both parts develop into new organism
- Budding: Part of organism develops by mitosis on parent then release as independent organism
- Parthenogenesis: Females produce offspring with no fertilization via diploid egg; typically female offspring
Give an example of:
Parthenogenesis
(Use one that Dr. McNeil may include on the exam)
The Pea Aphid
* The pea aphid male and female mate in the fall
* Diapausing eggs are laid, which are dormant until spring
* Parthenogenetic female colonies arise to increase number of aphids
* Repeats
(The haploid male drone bee example may also be used)
Define:
Sexual reproduction
Combines alleles/DNA from two different roganisms to create variation in the offspring
Describe how:
Organisms evolve through sexual reproduction
(What happens in sexual reproduction that leads to evolution)
- Random mutations that can either be combined in a new organism
OR
- Lost from the gene pool as only 50% of parent is passed on to next generation
List and explain the:
Benefits of sexual reproduction
- Variation in offspring genotype: Each individual is unique which gives a lot of options for selection to act on in a population
- Evolutionary change: Can combine beneficial traits by chance which increases speed of adaptive evolution
- Avoid Muller’s Ratchet: Harmful mutations may be lost from the gene pool by chance as organisms only pass on half of their genome
Additional Info:
What is the Lottery Principle?
(Applies in sexual reproduction)
Where variation is good if the environment changes
List and explain the:
Problems of Sexual Reproduction
- Cost of mating: Time consuming, risky with predation or diseases, invest in courtship behaviors, competition between genders
- Cost of meiosis: Only half of your alleles are inherited for next generation
- Cost of Males: Are not able to reproduce/carry offspring, so half of the population cannot contribute new members to the population from their body
List and explain:
The types of sexual reproduction in plants
- Dioecious: Every organism is either a male or a female with separate reproductive parts, but cannot be both
- Hermaphrodite: Sex organs occur together in same structure/flower, simultaneously acting as a male and female
- Monoecious: Separate male and female sex organs in the same individual but in different structures, such as plants with different flowers for male or female parts
Addional Info:
Can hermaphrodites self-fertilize?
Yes, they MAY self-fertilize but will first attempt to outcross
Give an example of a(n):
Dioecious plant
Ginkgo trees
Give an example of a(n):
Hermaphrodite plant
Roses
Give an example of a(n):
Monoecious plant
Corn
List and explain the:
Types of fertilization/pollination
- Abiotic: Wind/rain
- Biotic: Another organism faciliatates through co-evolution so that their structures can “match” each other
Example of biotic: Butterflies
List and explain the:
Types of sexual reproduction in animals
- Monoecious hermaphrodites: Both structures at the same time, prefer outcrossing (most cannot self-fertilize)
- Sequential hermaphrodite: Sex change occurs at some point in development
Give an example of a(n):
Monoecious hermaphrodite
Worms (they can line up ends and either give or receive sperm)
Explain an example of a(n):
Sequential hermaphrodite
Cinnamon clownfish
* All were born as males
* Largest member in group changes to female
* When that solo breeding female dies, the next largest MALE CHANGEST TO FEMALE
* A non-breeder then changes to a male
Define:
Protandry
- Male to female change
OR - An initial advantage being a male, but a later advantage to be a larger female if you survive that long
(The cinnamon clownfish is an example of protandry)
Define:
Protogyny
- Female to male change
OR - An initial advantage being a female, but a later advantage to be a larger male if you survive that long
Define:
Sexual Selection
A form of natural selection that is based on an organism’s ability to attract a mate (physical traits, safety, resources etc.)
Define:
Sexual dimorphism
Differences in traits between males and females
What is the result of sexual selection?
The “attractive” individuals will mate at a higher rate, which ensures that their offspring will inherit the desirable trait
Who is usually the “choosier sex? Why?
Usually female is choosy because of greater parental investment in care, and fewer eggs/larger cell size than males (equals limited attempts)
Explain the:
Tradeoffs’s of sexual selection
A trait that makes you a desirable mate (Colorful, loud mating call, long courtship dance) = Higher risk for predation
Too quiet/camouflaged = Lower mating rate and lower fitness
In the mating game,
What is the goal of males?
To mate with highest number of females, want max quantity of offspring
In the mating game,
What is the goal of females?
To mate with “best” mate option, want max quality of offspring
Compare the potential fitness and average fitness of:
Human males and females
Males:
* Higher POTENTIAL fitness (humans could have many mates pregnant at same time)
* Same AVERAGE fitness, typically monogamous
Females:
* Lower POTENTIAL fitness (Humans can only be pregnant sequentially one after another with long generation time)
* Same AVERAGE fitness, typically monogamous
Define:
Fitness
Ability to survive and reproduce
Define:
Absolute fitness
Number of viable offpsring an individual has
E.x. Meg has absolute fitness of 2 (equals 2 children)
Define:
Relative fitness
Number of offspring had versus other individuals (divide by max fitness from an individual in the population)
E.x. Meg’s sister has 16 kids, Meg’s relative fitness is 2/16
Define and give examples of:
Sex-Role Reversal
Males are choosy while females compete for access to males
* Giant water bug: Male carries eggs to hatch, so greater investment equals more choosy
* Crickets: Normally female is choosier and male cricket gives female ampulla of food when mates. However in low food conditions, the male becomes choosy
* Seahorses: Male provide parental care, females compete for access to males
List the:
Direct and Indirect benefits of being choosy
Direct benefits
* Provided by the opposite sex, a benefit to mate (E.x. resources, safety, gifts)
Indirect (genetic) benefits
* Choice for traits that indicate genetic quality, that can be passed down to the next generation so offspring benefit
List:
Some examples of indirect/genetic benefits of being choosy
- Good genes for desirable traits that indicate high genetic quality (bilateral symmetry in faces)
- Sexy sons - hope sons will inherit father’s preferred phenotype
- MHC alleles
What if both sexes are heavily invested in parental care?
Then both sexes are choosy and compete for access to the opposite sex
E.x. Humans, penguins
Define:
Mixed reproductive strategy
Depending on current needs (Long-term vs. short-term) will choose mates differently
List and explain:
Mating strategies
- Monogamy: Have one mate
-
Polygamy: Have one gener that has multiple mates from the opposite gender, further divided into:
1. Polygynous: One male, harem of females
2. Polyandrous: One female, many male mates
List and describe:
Courtship Behaviors
- Visual cues: Appearance (dimorphic) is a signal
- Auditory cues: Sounds waves or vibrations
- Olfactory signals/pheromones: Emit a chemical, perceived by others
- Tactile cues: Touch, dance, interaction that often follows a distinct pattern or sequence, if not done correctly mating would not occur
Give an example of each:
Courtship Behavior
- Visual cues: Redwing blackbirds, saturation of red color on wing indicates health
- Auditory cues: Elephants (sound waves), water strider (vibrations)
- Olfactory signals/pheromones: MHC alleles in human, smell preference
- Tactile cues: Bird dances
List a disadvantage of each:
Courtship Behavior
- Visual cues: MUST be in sight, wouldn’t work well if low visibility
- Auditory cues: MUST be a close distance to hear them/feel them
- Olfactory signals/pheromones: May travel long distances and persist, maybe not great in windy conditions
- Tactile cues: Must perform properly, must be within close proximity, but may not require on other cues
List and explain:
Types of Competition for Sex
- Intersexual: Between opposite sex, where individuals in 1 sex often choose the best mate in the opposite sex
- Intrasexual: Between same sex, where individuals in 1 sex often compete for access to the opposite sex
True or False:
Both inter- and intrasexual competition can occur at the same time
True
List and explain different types of:
Selection Pressures
- Mate Access: Chimps try to mate with multiple females, and females with multiple males, thus a selection pressure to produce more sperm and have large testicles
- Remove previous mating sperm: Dragonflies have modified penis to pack down (unusable) or scrap out (removal) of sperm from past mating (the male also holds onto female after mating for potentially days to prevent additional matings
- Require a reward: Scorpion fly male brings female a meal to eat while mating, better meal equals better chance of mating (sometimes the female stops mating at 14 minutes, 1 minute before the sperm transfer)
- Bilateral symmetry indicating “good developmental genes”: Birds with symmetrical tail feathers (e.x. turkeys, peacocks), tigers with symmetrical stripes on their face, moths with bilateral hair the same size have better chance of mating