Circulation & Reproduction Flashcards
(34 cards)
1
Q
Explain the circulatory system
A
Mammals require circulatory system to work over large distances - high metabolic demands
2
Q
What are the 3 components to the circulatory system?
A
- Fluid
Blood or hemolymph
- Pump
Heart
- Vessels
Vascular components: arteries, veins, capillaries
3
Q
What are vessels?
A
- Two types of vessels in the cardiovascular system
Oxygenated blood leaves heart through arteries
Deoxygenated blood returns to heart through veins - Gases are exchanged across thin walled capillaries
4
Q
What about the pump?
A
- Heart is segmented (Number of chambers differs among taxa)
- Fish
2 chambers (1 atrium and 1 ventricle)
Single ;loop circulatory system - Amphibians & most nonavian reptiles
3 chambers (2 atria and 1 ventricle)
Double loop circulatory system
Some mixing of deoxygenated and oxygenated blood - Crocodiles, Birds & Mammals
4 chambers (2 atria, 2 ventricles)
Double loop circulatory system
Most efficient
5
Q
What are the 2 opposing strategies for reproduction?
A
r-selected reproduction
k-selected reproduction
6
Q
What is r-selected reproduction?
A
- Short life expectancy
- Many offspring (thousands)
Low % survival - No parental care
Cultural memes not passed down
No parental nourishment
7
Q
What is k-selected reproduction?
A
- Long life expectancy
- Few offspring
High % survival - Parental care
Cultural memes passed down
Nourish embryo
8
Q
Most r-selected to most k-selected
A
Bacteria Molluscs Insects Fish Amphibians Reptiles Mammals Apes Human
9
Q
What are their types of sexual reproduction?
A
- Bisexual Reproduction
Most common form
Male and female gametes (sperm or egg) are produced
Two haploid (n) gametes combine to form a zygote (2n) - Hermaphroditism
Male and female organs occur in sam individual
Most avoid self fertilization - Parthenogenesis (can also be categorized as asexual)
Embryo develops from unfertilized egg (sperm may activate but not fuse with egg)
10
Q
What are the types of hermaphroditism?
A
- Simultaneous
Active female and male organ at the same time - Sequential
Active sex changes at some point during life
11
Q
Explain in more detail parthenogenesis
A
- Development of embryo from unfertilized egg
- Referred to as an incomplete form of sexual reproduction
Offspring are formed from gametes but only one parent contributes genetic material - Two types
Haploid
Diploid
12
Q
What is haploid parthenogenesis?
A
- Haploid ovum formed by meiosis
- Rare occurs in some bees and nematodes
13
Q
What is diploid parthenogenesis (results in diploid offspring)?
A
Case 1: meiosis occurs but diploid condition is restored
- Chromosomal duplication
- Autogamy (rejoining of haploid nuclei)
- Offspring are not clones of parent (recombination occurs)
Case 2: no meiosis occurs
- This is considered an asexual form of parthenogenesis
- Offspring are clones of the parent
14
Q
How is reproduction done in fishes?
A
- Mostly dioecious, external fertilization, oviparous
Also instances of: monoecious, internal fertilization, ovoviviparous, viviparous - Often release vast numbers of gametes
e.g large female cod will release 4-6 million eggs in a single spawning
This reproductive strategy is associated with lower parental investment in the offspring - r selected reproduction
15
Q
What are the general patterns of reproduction in fish?
A
- Pelagic (open sea) marine teleosts
e.g. Norther cod
Minute, buoyant, transparent eggs
Eggs hatch into larvae as they float in the ocean - Near shore and benthic (bottom dwelling) fish
Larger eggs, with more yolk
Non buoyant, adhesive
Eggs are buried, attached to vegetation, deposited in nests
Many benthic fish guard their eggs (male)
16
Q
What is sequential hermaphrodite in clown fish?
A
- Live in social groups (in symbiosis with sea anemones)
- Group consists of a breeding pair (one male, one female) and a number of undifferentiated fish
- If the female dies, the adult male becomes female, and one of the smaller fish takes his place
17
Q
What is another unusual reproduction in fish?
A
- Amazon Molly (all female species)
- Egg is diploid when it is laid (no meiosis)
- Male sperm from a related species may be required to stimulate the egg
- Offspring are clones of the mother
- This is parthenogenesis
18
Q
How is the reproduction done in birds?
A
- Dioecious
- All oviparous
- Generally no external genitalia (some ducks have penises)
- Cloaca
Opening to the reproductive system in males and females
Opening for the intestinal and urinary tract - Internal fertilization by cloacal kiss
19
Q
How do birds lay eggs?
A
- Female generally lays one egg per day until she has a full clutch
Determinate layers: produce a certain number of eggs and stop
Indeterminate layers: replace eggs if some are removed
20
Q
How is the mating system in birds?
A
- Over 90% of avian species are monogamous
- Two types of mating systems in animals
Monogamy: an individual has only one mate
Polygamy: an individual has more than one mate during breeding period - Some birds mate for life
Remain with partner throughout the year
Meet up each year in the breeding grounds - Often both sexes participate in parental care
Different from mammals where there is an unequal investment
21
Q
What is polygyny in birds?
A
- E.g. sage grouse gather in a collective display ground
- Males defend individual territories and display
- Females tend to choose the dominant male
22
Q
What is polyandry in birds?
A
- E.g. spotted sandpiper
- Female will mate with several males
- She lays multiple clutches of eggs which individual males care for
23
Q
What are the developmental states of chicks?
A
Precocial
Altricial
24
Q
Explain precocial
A
- Hatch covered with down
- Can run or swim as soon as they hatch
- Most can’t fly
- Fairly independent, but still fed and protected from predators for some time
25
Explain altricial
- Smaller eggs, less yolk (less investment)
- Hatch naked (no feathers)
- Unable to see or walk at hatch
- Remain in the nest for 1-2 weeks or more
- Must be fend constantly by parents
26
How is reproduction in mammals?
- Defined mating seasons
Winter or spring
Timing of birth corresponds with warmer weather
- Delayed implantation lengthens the gestation period in some mammals
Blastocyst doesn't implant in the uterine wall immediately
Gestation is extended so that the timing if birth is favourable
- Male mammals fertile at any time; Timing of female fertility is restricted by the estrous cycle
27
What is the estrous cycle?
- Estrous = period of heat of a female mammals associated with ovulation
- Monoestrous: single estrus during breeding season
- Polyestrous: recurrence of estrus during breeding season
- Menstruation = discharge of blood and uterine endometrial tissue at the beginning of the menstrual cycle
Most animals reabsorb the endometrial tissue
Humans, chimps, elephant shrews and some bats discharge it
28
What are the reproductive patterns in mammals?
Three different patterns of reproduction in mammals:
- Monotremes
- Marsupials
- Placental mammals
29
What are monotremes?
- Large, yolky eggs
- Earliest mammals laid eggs, and monotremes have retained this characteristic
- Egg laying (oviparous) mammals
- All live in Australia or New Guinea
- Very small group: Platypus and 4 species of echidna
- Embryos develop in uterus for 10 to 12 days (nourished through yolk)
- Thin, leathery shell is secreted around the embryos
- Eggs laid in a burrow (platypus) or mothers pouch (echidna)
- Hatch after 12 more days
- Drink milk produced by mothers mammary glands
No nipples, so monotreme young lap milk from fur on mothers belly
30
What are marsupials?
- Embryos develop in mothers uterus but do not implant
- Born at a premature stage; complete development outside of uterus
- Viviparous mammals characterized by premature birth
- Most have specialized pouches where they continue to nurse and protect the young after birth
- Viviparous mammals (young are born premature)
- Transient placenta (yolk sac placenta)
- Gestation is short (young are tiny: effectively still embryos)
- Lactation and parental care is long
- Some (not all) have pouches
31
What is the distribution of marsupials?
- Most found in Australia and New Guinea (approx. 200 species)
Kangaroos, wallabies, wombats, koala, Tasmanian devil, possums
- Some found in the Americas (approx. 70 species)
Opossums
One North American species: Virginia Opossum
32
What are the placental mammals?
- 94% of mammals are placental
- Embryo is nourished through the placenta in the uterus
- Viviparous
- Prolonged gestation
Contrasts with marsupials
- Embryos remain in the uterus nourishment by food supplied by the placenta (formed from amniotic membranes)
- Gestation period generally increases with animal size and lifespan
Elephant (22 months)
Mouse (21 days)
33
What is the placenta?
- Placenta is a modified amniotic egg
Amnion surrounds embryo with amniotic fluid (as in other animals)
Allantois, yolk sac, and part of chorion contribute to the placenta
Chorion surrounds entire thing and breaks as labour breaks
- Placenta attaches embryo to mothers uterine wall
Air, food, and waste are transferred across the placenta
34
What is the developmental state at birth for mammals?
- Like birds, mammals can be
Altricial (immature and helpless)
Precocial (mature and mobile)
