Lecture 1 (1a&b) - Maximizing Reproductive Success Flashcards
1
Q
What is the purpose of reproduction?
A
- the processs by which parents produce the first filial generation
- parental generation produces offspring = first filial generation F1
- F1 generation acts as parents to F2
- purpose of reproduction is to produce the 2nd… filial generation
2
Q
Lifetime reproductive output
A
- number of offspring born to a parent in the F1 generation
- LRO = product of fecundity (fertility) x fertile lifespan
(number of offspring x # of time you reproduce)
3
Q
What determines LRO?
A
- fecundity
- semelparous vs iteoparous
- fertile lifespan
4
Q
Fecundity
(dependent upon…)
A
- number of fertile matings
- mate density
- success in courting (and retaining a mate)
- success in mating
- fertility of individual
- feterility of partners (sexual reproduction)
5
Q
Semelparous
A
a single episode of reproduction before death
(eg pacific salmon)
6
Q
Iteroparous
A
several rounds of reproduction before death
- with same partner = monogamous
- with different partners = polygamous
polygamy:
- polygynous = 1 male, several females
- polyandrous = 1 female, several males
7
Q
Fertile life span
(dependent upon…)
A
- age at first fertile mating
- rate of devolopment (precocity)
- success in courting a mate
- success in mating
- age at last fertile mating (~= survival)
- usually determined by death
- menopause is rare
- ie mating not until death
- but exists in human females and elephants
8
Q
What is lifetime reproductive success?
A
- number of fertile offspring born to a parent in the F1 generation
- number of offspring attributable to a “grandparent” in the F2 generation
9
Q
When might lifetime reproductive success be less than lifetime reproductive output?
A
sterile matings
- eg mule is sterile
- mule = mother is a horse
- hinney = mother is a donkey
- eg tigons and ligers have decreased fertility
- liger = mom tiger
- tigon = mom lion
- lions in Africa, tigers in Asia = geographically reproductively isolated
10
Q
What determines lifetime reproductive success?
A
- LRO
- fecundity/fertility of F1
- probability that F1 survive to sexual maturity / achieve fertility
- LRS WILL ALWAYS** BE LESS THAN LRO**
11
Q
Types of asexual reproduction
A
- binary fission
- multiple fission
- budding
- fragmentation
- vegetative propagation
- apomixis
- parthenogenesis
12
Q
Binary fission
A
- parent cell splits into two identical daughter cells
- uses just mitosis
- mother cell is gone
- eg archaea, eubacteria
13
Q
Multiple Fission
A
- parent cell replicates nucleus then splits into several identical daughter cells
- mother cell gone also
- eg protista
14
Q
Budding
A
- “daughter” cell divides from “mother cell”
- mother still exists (unlike binary and multiple fission)
- eg S. cerevisiae and hydra
15
Q
Fragmentation
A
- offspring regenerate from fragments (fissiparity)
- eg annelids, turbellarians, starfish
16
Q
Vegetative propagation
A
- plants and fungi
- similar to fragmentation
- new plants develop from the buds of the runner in eg strawberries
17
Q
Apomixis
A
- agamospermy
- in plants
- asexual seeds
- no meiosis or gametes
- seeds not formed by fertilization by sperm
- eg dandelions in absence of pollinizing insects
18
Q
Parthenogenesis
A
- in animals
- unfertilized “egg” forms embryo
- invertebrates: Daphnia, rotifers, aphids, stick insects, hymenoptera (including parasitic wasps)
- vertebrates: bonnethead shark (females make babies), komodo dragos, green whiptail lizards (?), turkeys
- not naturally in mammals
19
Q
Pros of ASEXUAL REPRODUCTION
A
- simple - only need 1 type of cell division (mitosis)
- can occur in absence of partner (fast)
- avoid risks intrinsic to sexual reproduciton (eg predation, physiological stress, disease)
20
Q
Cons of ASEXUAL REPRODUCTION
A
- all offspring are clones
- can’t select for favorable traits
21
Q
Cons of SEXUAL REPRODUCTION
A
- requires second type of cell division
- reproductive division from diploid to haploid (meiosis)
- required to locate/select/court/mate with a partner
- dilution of alleles (only 50% related to F1)
- entrust future of female alleles
- high energetic cost
- producing germ cells
- locating/courting partner
- mating
- nourishing and nurturing offspring
- high biological risks
- untested alleles (?)
- predation
- disease
22
Q
Pros of SEXUAL REPRODUCTION
A
- genetic variation between offspring
- 2 genetically dissimilar parents
- diakinesis (recombination of grandparental genes)
- raw material for evolution
- sexual species have highly evolved features
- eg CVS, CNS
23
Q
Which is better - sexual or asexual reproduction?
A
- if the environment is stable –> asexual reproduction is better
- but generally sexual reproduction is better
- CONTEXT DEPENDENT
24
Q
How can a sexually reproducing organism maximize its LRO?
A
- maximize number of reproductive partners (polygamy should be the rule)
- maximize the number of germ cells produced
- maximize the probability of fertilization
- minimize the interval between offspring
- gestation short and quick
- have another baby quickly after the last one
25
Strategy for flowering plants (angiosperms)
* multiple partners
* lots of germ cells (pollen)
* fertilization by wind, water, animals
* seasonal production of seeds
* season for producing seeds and season for setting seed
26
Strategy for aquatic invertebrates
* multiple partners
* lots of germ cells (eggs and milt)
* fertilization in water "by chance"
* a "numbers game"
27
Strategy for elasmobranchs and teleosts
* multiple partners
* lots of germ cells (eggs and milt)
* fertilization in water at spawning grounds (timed external fertilization)
* not random, timed/synchronized, external fertilization
* fertilization can be internal
28
Strategy for amphibia
* polygamy
* lots of germ cells (eggs and sperm)
* fertilization in water at spawning
* synchronous external fertilization or
* indirect internal fertilization
* eg salamanders (female walks over sperm, taken up)
29
Strategy for rerrestrial invertebrates
* polygamy and monogamy
* lots of germ cells (eggs and sperm)
* fertilization - indirect or direct internal
* spermatophore/intromissive organ
* sperm can't be left outside on land - dries out
30
Strategy for terrestrial vertebrates
* polygamy and monogamy
* fewer germ cells (eggs and sperm)
* fertilization (internal)
31
Purpose of egg
* yolk sac for nourishment
* keeps egg sac from drying out
* reproduction needs fluid
32
Reptilian vs Avian eggs
* avian eggs = completely impervious to gasses - cracks
* reptile eggs permeate to gas - tears
33
Strategy for mammals
Stages of development
* oocyte - female germ cell, haploid (via meiosis)
* zygote - diploid, joining of male and female germ cells, ~ single-celled embryo
* embryo - organogenesis, ball of cells developing
* fetus - once all organs are present (after about 6 weeks in mammals, then just grows)
* infant - newborn
34
When is a mammal born?
see different types of mammals
35
Types of mammals
* Protheria = monotremes
* Metatheria = marsupials
* Eutheria = placental
36
Protheria
* monotremes
* mammals that lay eggs instead of giving birth to live young
* eg echidna, platypus
* lay eggs that stay in the pouch
* leathery eggs - like reptiles
* inside egg = embryo (already fertilized)
* only one with chance to survive without parent
37
Metatheria
* contains placental mammals, and others
* living mammals with abdominal pouches
* eg kangaroos, possums, etc
* accommodate neonates in abdominal pouches
38
Eutheria
* placental mammals
* give birth to live young
39
Strategy for eutheria
* polytocus - producing many offspring in a single birth
* several oocytes to several embryos
* monotocus - producing a single offspring in a single birth
* ~ single embryos
40
Modes of reproduction
Species can be...
* oviparous
* viviparous
* ovoviviparous
41
Oviparous
* lay **eggs**
* pre-/post-fertilization
* **nutrition **from egg **yolk**
* lay eggs with little/no embryonic development within the mother
42
Viviparous
* give birth to **live young**
* **nutrition **from **parent**
* eg placenta
* development of the embryo inside the body of the mother
43
Ovoviviparous
* give birth to ** live young**
* **nutrition** from egg **yolk**
* embryos develop inside eggs that are retained within the mother's body until they are ready to hatch
44
Modes of reproduction
species can be:
* r-selected
* K-selected
45
r-selected species
* reproduce and develop **rapidly**
* highly **prolific**
* eg polytocus
* **little/no parental** investment
* eg most insects
46
K-selected species
* reproduce a d develop **slowly**
* **few offpring**
* eg monotocus
* **high **level of **parental investment**
* eg humans
* population may be at carrying capacity
47
What determines LRS?
* LRO
* fecundity/fertility of F1
* probability that F1 survive to sexual maturity / achieve fertility
* because this probability is usually less than 1, LRS is always less than LRO
48
What would influence the probability of offspring surviving to sexual maturity?
* rate of development
* precocious = fast
* survival
* starvation (most likely)
* predation
* disease
which of these can a parent influence and how?
* rate of development
* fed more = faster development (with genetics too)
* starviation
* bring food/milk
* help avoid predation
49
Reproduction and development are...
interdependent
parenting can influence both
50
Balancing investment
producing gametes side = aquatic invertebrates (can't control where sperm/eggs go)
parental care side = mammals
51
