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Organisms 2 > Lecture 22 > Flashcards

Lecture 22 Flashcards

1
Q

Organisms with no circulatory system

A
  • Protozoans
  • Porifera
  • Cnidaria
  • Ctenophora
  • Platyhelminthes
  • Nematoda
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2
Q

Organisms with open circulatory systems

A
  • Most molluscs
  • Arthropods
  • Echinoderms
  • Hemichordates
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3
Q

Organisms with closed circulatory systems

A
  • Cephalopod molluscs
  • Annelids
  • Chordates
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4
Q

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
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5
Q

Heart segments for different animals

A
  • Fish
  • Two chambers (1 atrium and 1 ventricle) • Single loop circulatory system
  • Amphibians & most nonavian reptiles
  • Three-chambers (2 atria, 1 ventricle)
  • Double loop circulatory system
  • Some mixing of de-oxygenated and oxygenated blood
  • Crocodilians, Birds & Mammals
  • four-chambers (2 atria, 2 ventricles)
  • Double loop circulatory system
  • Most efficient
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6
Q

r-selected reproduction

A
  • short life expectancy
  • Many offpring (thousands)
  • Low % survival
  • No parental care
  • Cultural memes not passed down • no parental nourishment
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7
Q

K-selected reproduction

A
  • Long life expectancy
  • Few offspring
  • High % survival
  • Parental care
  • Cultural memes passed down
  • Nourish embryo
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8
Q

MOST r-selected and k- selected

A 
MOST R 
 •Bacteria 
• Molluscs 
• Insects
• Fish
• Amphibians
 • Reptiles
• Mammals
• Apes
• Humans
MOST K
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9
Q

Parthenogenesis

A

• development of embryo from unfertilized egg
Note: The egg is a sex cell!
• Referred to as an ‘incomplete form of sexual reproduction’
• Offpring are formed from gametes but only one parent contributes
genetic material

  • Two types of parthenogenesis
  • Haploid Parthenogenesis
  • Diploid Parthenogenesis
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10
Q

Haploid Parthenogenesis (results in haploid offspring)

A
  • Haploid ovum formed by meiosis

* Rare…occurs in some bees and nematodes

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11
Q

Diploid Parthenogenesis (results in diploid offspring):

A
  • Case1: 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 parthenogeneis
  • Offspring are clones of the parent
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12
Q

Reproduction 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

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13
Q

General Patterns of Reproduction of fish

A
  • Pelagic (open sea) marine teleosts
    • e.g. Northern 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)
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14
Q

Sequential hermaphrodite – clown fish

A
  • 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
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15
Q

Amazon molly reproduction

A 
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
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16
Q

Reproduction 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”

17
Q

Egg Laying for birds

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

18
Q

Mating Systems for birds

A

• Over 90% of avian species are monogamous

Two types of mating systems in animals:

• Monogamy: an individual has only one mate (theoretically!)

  • Polygamy: an individual has more than one mate during breeding period
  • Some birds mate for life,
  • remain with partner throughout the year (e.g. geese, swans), or meet up each year in the breeding grounds or..

• Often both sexes participate in parental care
different from mammals where there is an unequal investment

19
Q

Polygamy in birds (not common)

A

• Polygyny (many females, one male)
Females tend to choose the dominant male

• Polyandry (many males, one female)
Female will mate with several males, lays multiple clutches

20
Q

Developmental State of Chicks

A
  • Precocial
  • Hatch covered with down
  • Can run or swim as soon as they hatch
  • Most can’t fly
  • Fairly independent,
  • Altricial
  • Smaller eggs, less yolk (less investment)
  • Hatch naked
  • Unable to see or walk at hatch
  • Remain in the nest for 1-2 weeks or more
  • Must be fend constantly by parents
21
Q

Reproduction in Mammals

A

• Defined mating seasons

  • 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 of birth is favourable
  • Male mammals fertile at any time; Timing of female fertility is restricted by the estrous cycle
22
Q

Estrous Cycle

A

Estrous = period of heat of a female mammal associated with ovulation
• Monoestrous: single estrus during breeding season • E.g. dogs, foxes, bats
• Polyestrous: recurrence of estrus during breeding season• E.g. field mice. Squirrels

• 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
23
Q

Reproductive Patterns In mammals

A

Monotremes
• Large, yolky eggs
• Earliest mammals laid eggs, and monotremes have retained this characteristic

  • Marsupials
  • Embryos develop in mother’s uterus but do not implant
  • Born at a premature stage; complete development outside of uterus
  • Placental Mammals
  • 94% of mammals are placental
  • Embryo is nourished through the placenta in the uterus
24
Q

Monotremes development

A
  • 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 mother’s pouch (echidna)
  • Hatch after 12 more days
  • Drink milk produced by mother’s mammary glands
  • No nipples, so monotreme young lap milk from fur on mother’s belly
25
Q

Marsupials development

A
  • 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
26
Q

Placental Mammals development

A

• Viviparous
• Prolonged gestation
• Contrasts with marsupials
• Embryos remain in the uterus nourished by food supplied
by the placenta (formed from amniotic membranes)
• Gestation period generally increases with animal size and lifespan

27
Q

Placenta

A

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 begins
• Placenta attaches embryo to mother’s uterine wall
• Air, food, and waste are transferred across the placenta

28
Q

Like bird reproduction , mammals can be

A
  • altricial (immature and helpless)

* precocial (mature and mobile)

Organisms 2 (23 decks)

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