1. 1. SEXUAL AND ASEXUAL 2. LIFE CYCLES OF PLANTS AND INSECTS 3. FLOWERS AS REPRODUCTIVE STRUCTURES 4. REPRODUCTIVE STRATEGIES IN ANIMALS

2. COMPARING ASEXUAL AND SEXUAL REPRODUCTION Definition of asexual reproduction: No fertilisation Only one parent No genetic variation as opposed to... Lorraine Kuun, July 2011

3.  Fertilization  Two parents  Genetic variation  Gametes fuse to form zygote, containing genes from both parents.  Further variation brought about by: 1. Crossing over during meiosis, prophase I 2. Random assortment and segregation of chromosomes 3. Random fertilisation 4. Mutations Lorraine Kuun, July 2011

4. Types of asexual reproduction 1.Binary fission – “splitting in two” – mitosis, e.g. bacterium: Escherichia coli Lorraine Kuun, July 2011

5. Types of asexual reproduction 2. Budding – new individual develops as outgrowth on parent organisms e.g. Yeast cells. Lorraine Kuun, July 2011

6. Types of asexual reproduction 3.Spore production – spores produced during favourable conditions e.g. Fungi Lorraine Kuun, July 2011

7. Types of asexual reproduction 4.Vegetative reproduction – vegetative part of plant, i.e. root, stem of leaf develops into new plant; can be natural or artificial. Lorraine Kuun, July 2011 Buds on leaf margins e.g. Kalanchoe

8. NATURAL – Runners, Rhizomes and bulbs and tubers Bulbs Tubers

9. ARTIFICIAL: Cuttings, Grafting and tissue cultures

10. ADVANTAGES OF ASEXUAL REPRODUCTION Lorraine Kuun, July 2011

11. DISADVANTAGES OF ASEXUAL REPRODUCTION 1.No genetic variation – adaptation may be difficult 2.All share same “weak characteristics” – may die out when environmental conditions change/become unfavourable 3.Mass reproduction can threaten environment – carrying capacity Lorraine Kuun, July 2011

12. ADVANTAGES OF SEXUAL REPRODUCTION 1.Genetic variation 2.Possible better adaptations to changing environment 3.Role in natural selection 4.Better chances of survival Lorraine Kuun, July 2011

13. DISADVANTAGES OF SEXUAL REPRODUCTION DISADVANTAGES OF SEXUAL REPRODUCTION 1.High energy cost – gametes to be produced, gestation, parental care etc. 2.Needs two parents 3.Slower, longer process 4.Young can be vulnerable to predators 5.Extended periods of parental care 6.Plants may need pollinators Lorraine Kuun, July 2011

16. 1.Gametophyte: generation producing gametes in gametangium/ gametangia sexual stage. 2.Sporophyte: generation producing spores in sporangium/ sporangia – asexual stage. NB: In higher plants the generations alternate in the life cycle of a plant; in lower plants reproduction is either through gametes (sexual) or spores etc. (asexual).

17. 1.A haploid gametophyte generation that produces gametes (n) by mitosis... the gametes (n) fuse to form zygote (2n), the start of... 2.A diploid sporophyte generation that produces spores (n) by meiosis.

19. Leaf-like structures of moss gametophyte Sporangium of moss sporophyte

24. INSECT METAMORPHOSIS

25.  Physical changes from one stage in life cycle to another.  TWO TYPES OF METAMORPHOSIS:  1.Complete metamorphosis  2.Incomplete metamorphosis

26. 88 % of all insects12 % of insects  COMPLETE  Four stages:  1.egg  2.larva  3.pupa  4.adult  E.g. Butterflies, bees, housefly  INCOMPLETE  Three stages:  1.egg  2.nymph  3. adult  E.g. Locust, cricket, cockroach

30.  Advantages: 1. Vulnerable pupa stage avoided. 2. Less energy is needed – no drastic changes from pupa to adult. 3. All stages can eat same food.  Disadvantages: 1. Nymph and adult often compete for same food. 2. Insect vulnerable to dehydration and predators when moulting. 3. Entire insect population could be threatened by environmental changes.

32. Lorraine Kuun, July 2011

37.  1.Male (no pistil) or female (no anthers) flowers on different plants – dioecious.  2.Protandry – pollen ripe before stigma is receptive.  3.Protogyny – stigma receptive, but pollen not ripe yet.  i.e. self-pollination is prevented. Lorraine Kuun, July 2011

38.  Most pollinators are insects e.g. Bees, moths, butterflies, beetles.  Some vertebrates also pollinate flowers e.g. Bats, mice, birds (mainly).  Many flowers are pollinated by wind. Lorraine Kuun, July 2011

39.  Bright colours (bees cannot see red), white for night pollinators e.g. moths  Often sweet scent (attracts moths and butterflies)  Reward of nectar and pollen  Contrasting markings on petals to locate centre of flower (usually not visible to human eye – ultraviolet)  Pollen cling to hair on insect bodies Lorraine Kuun, July 2011

40.  High yield of dilute nectar  Bigger than most insect-pollinated flowers  Open in daytime, often red  Sturdy against rough feeding of birds  Little or no scent – birds have poor sense of smell  Protect ovary against beaks by being inferior or by partition  Pollen sticks together in clumps  Often erect or with landing platform for birds that do not hover Lorraine Kuun, July 2011

41.  Flowers do not have scent, nectar or brightly coloured petals – no need to attract pollinators.  Flowers high on plant to be exposed to wind.  Flowers usually small and reduced, lacking calyx or corolla (sepals and petals).  Anthers large and well-exposed.  Masses of light, non-sticky pollen produced.  Stigmas long and feathery with large area for trapping pollen. Lorraine Kuun, July 2011

45. The ovary develops into the fruit, the ovule into the seed.  The fruit develops from the following layers: Fruit wall from ovary wall. Seed from ovule. Lorraine Kuun, July 2011

46.  A seed consists of a 1.Seed coat – outer layer of ovule (pericarp). 2.Embryo – from fertilisized egg cell (zygote undergoes mitosis). Lorraine Kuun, July 2011

47. Endosperm – result of double fertilization. Endosperm is food for embryo – also why we eat seeds for food. Lorraine Kuun, July 2011

48.  Resistant to unfavourable conditions as they have seed coat.  Can be dispersed effectively (see later).  Can remain viable in dormant state for long periods.  Seeds have stored food reserve in endosperm or cotyledons; includes starch, oils and or protein.  Important to man as they are cheap form of plant propagation, way to store plants and are a store of food. Lorraine Kuun, July 2011

49.  Dormancy is a state of rest. Embryo inactive, seed will not germinate.  Some plants have obligatory period of dormancy – seed will not germinate even if conditions are favourable.  Dormancy prevents seeds from hatching in wrong season when seedlings would be exposed to unfavourable conditions. Allows seeds to survive unfavourable conditions.  Allows for seed dispersal agents to act. Lorraine Kuun, July 2011

50.  Wind – seeds are light with plumes or wings.  Animals – hooks and thorns – cling to wool, stick in paws.  Humans – edible fruit – seeds egested in different position.  Water – seeds contain oil or air bubbles – float away.  Self-dispersed – fruit dry, dehiscent. Lorraine Kuun, July 2011 Agents for seed dispersal

51. Lorraine Kuun, July 2011

52. COCO DE MER drifts along ocean currents Lorraine Kuun, July 2011

54.  Most important plant source of food for humans.  Practical form of food – easy to transport and store for long periods of time.  Grains – wheat, maize (mealies), sorghum, rice, oats; mainly starch  Pulses (legumes) – beans, peas, soy beans, peanuts, lentils, plant proteins  Nuts – oily seeds in hard shells e.g. walnuts, cashews, pecans etc. Lorraine Kuun, July 2011

55.  Many plant species under threat.  Seed bank stores seeds of wild plants and crops.  UK – conserves seeds of about 10% of wild plant species at Kew – Millennium Seed Bank Project.  Swedish International Seed Vault – reinforced concrete tunnel – 4,5 million seed samples – will remain viable for 1000’s of years.  MSBP working with SA National Biodiversity Institute – contributing 2500 indigenous species – endangered, endemic, over-exploited Lorraine Kuun, July 2011

56. Can be used to 1. re-establish damaged, lost habitats and ecosystems 2. re-introduce extinct, endangered or threatened species 3. provide research material Lorraine Kuun, July 2011 THANK YOU

57. THE ULTIMATE GOAL OF EACH SPECIES Lorraine Kuun, July 2011

58.  To produce the maximum number of surviving offspring...  while using the least amount of energy.  This is called the reproductive effort. Lorraine Kuun, July 2011

59. 1. Courtship 2. External vs Internal fertilisation 3. Ovipary, ovovivipary and vivipary 4. Precocial and Altricial development 5. Amniotic egg 6. Parental care Lorraine Kuun, July 2011

60.  Simple strategies include pheromones (chemical), brightly coloured body parts (visual) and mating calls (auditory) stimuli. Lorraine Kuun, July 2011

62.  Complex strategies, unique to species, include courtship displays, annual rut (period of sexual excitement), lek breeding system, courtship-feeding. Lorraine Kuun, July 2011

63. Courtship display strategies unique to each species; can include movement, calls, seasonal colour patterns etc. Lorraine Kuun, July 2011 Bluecrane male trying to attract female’s attention by an elaborate dance

64. 1. Females will be in peak condition to nurture developing baby. 2. Young are born when enough food is available to enable them to reach reproductive age. Lorraine Kuun, July 2011

66.  Above: male springbok display Left: male cichlids make bowers for females to lay eggs

67. Lorraine Kuun, July 2011 Male hoopoe feeds female; if she accepts, they will mate

68.  Males and females find suitable mates e.g. male with best genetic potential.  Sexual behaviour in courtship is timed so that male and female both ready for mating at same time.  Energy expenditure by male; female conserves energy for breeding. Lorraine Kuun, July 2011

69.  Disadvantages of external fertilisation (outside the body): 1. Wasteful; huge loss of energy – many eggs produced, few survive. 2. Fertilisation not certain. 3. Environmental conditions important for hatching of eggs Lorraine Kuun, July 2011

70. 1. Huge numbers of eggs increases probability of fertilisation. 2. Courtship rituals ensure that males and females are closer to each other. 3. Eggs of marine species release species-specific chemotactic factor to attract sperm. 4. Spawning is timed to occur when ocean currents can disperse eggs e.g. sessile species. 5. Young easily dispersed by sea currents; reduce competition. 6. No complicated physical mating, using energy. 7. Larval form gets food directly from environment; no energy input from parent. Lorraine Kuun, July 2011

71. Mating occurs, but no copulation

72.  Occurs in insects and terrestrial vertebrates i.e. birds, reptiles and mammals.  Marine mammals and some fish e.g. sharks and rays also have internal fertilisation.  Mating and copulation occurs.  Most animals have cloaca – common opening for reproduction and egestion – during fertilisation cloacas are lined up.  Male insects and mammals have a penis – organ to transfer sperm to body of female.  Fluid inside female provide medium for sperm to swim towards egg cell(s). Lorraine Kuun, July 2011

73. 1. Fertilisation is more certain – gametes placed closer together. Fewer gametes needed. 2. Energy saved in producing fewer gametes can be used for other purposes. Lorraine Kuun, July 2011

74. 1. Yolk to feed young. 2. Shells that enclose eggs (oviparity); better protection increases survival rate. 3. Some fertilised eggs very well-protected e.g. Sharks (ovoviviparity) and mammals (placenta). 4. Less wastage of gametes – in humans one egg per month produced. There is a disadvantage: a cooperative partner is needed! Lorraine Kuun, July 2011

76.  OVIPARY – eggs are released and develop outside body of female, fertilisation internal or external, egg yolk only nutrition.  OVOVIVIPARY – Internal fertilisation, egg shell soft, eggs hatch inside body, appears to be born alive, egg yolk nutrition, mother for protection.  VIVIPARY – fertilisation internal, no egg shell, nutrition via placenta. Lorraine Kuun, July 2011

77.  Most fish, amphibians and lower aquatic forms.  Needs large numbers of eggs.  Larval stage self-sufficient; don’t compete with parents – use different food sources.  Eggs and larvae easily dispersed. Lorraine Kuun, July 2011

78.  Invertebrates produce large numbers of eggs to ensure survival (no or little parental care).  Protective shell prevents embryo from drying out.  Fewer eggs in e.g. birds and reptiles – energy can be used for more food in egg (yolk and albumin), hatching and protection, parental care.  Development of amnion important factor in success. Lorraine Kuun, July 2011

79. Hard shell good protection for developing embryo; prevents embryo from drying out.

80. Lorraine Kuun, July 2011 Shark egg pouch with yolk clearly visible

81. 1. Fewer eggs needed – higher survival rate of offspring. 2. Developing embryo much less vulnerable to predators. 3. Developing embryo not subject to environmental changes e.g. temperature. 4. Young born fully developed, can feed and escape predators more easily. 5. Occurs in some invertebrates, fish and reptiles. Lorraine Kuun, July 2011

83. Young puff adder being “born alive” after hatching inside mother; note position of cloaca.

84.  Occurs in placental mammals, some sharks and scorpions  Fertilisation internal, no shell  Placenta responsible for nutrition – young born alive  1.fewer eggs necessary  2.energy available for nourishment and protection of embryo, as well as parental care Lorraine Kuun, July 2011

86. PRECOCIAL 1. Young hatch or born when almost fully developed 2. Open eyes, hair or down 3. Active or mobile 4. Not confined to nests 5. Energy goes into prenatal development ALTRICIAL 1. Born or hatched when not well- developed 2. Often naked, lacking hair or down 3. Cannot walk or fly 4. Confined to nest or burrow 5. Energy goes into parental care after birth Lorraine Kuun, July 2011

87.  Ground-nesting birds e.g. Penguins, domestic poultry, ostriches  Large mammals e.g. Elephants, species of antelope, horses etc  Allows young to fend for itself, feed and stay warm  Stay with herd for protection against predators  Learn from older individuals in herds  OFFSPRING HAS GOOD CHANCE OF SURVIVAL Lorraine Kuun, July 2011

88. Left: Penguin chick and Above: foal, both mobile soon after birth

89.  Small animals that produce big litters e.g. mice, rats, cats, dogs  Tree-nesting birds that have nests away from predation  Humans (see human reproduction)  Altricial species need parental care for a long time – usually female that does the caring, male sometimes involved.  Birds usually have mouth-lining or gape- edge  Mammals small and immature brains Lorraine Kuun, July 2011

90. Altricial bird – see mouth-lining that attracts mother

91. Lorraine Kuun, July 2011 Mice survive in broods, cared for by mother (left); Kittens born weak and totally dependent on mother (below)

92.  Adaptation of later vertebrates; can lay eggs in terrestrial environment.  Amniotic egg has fluid-filled, extra- embryonic membranes that prevents embryo from drying out.  Earlier vertebrates lay eggs in water; need to return to water/live in water to reproduce.  Amniotic egg lessens dependence on water for reproduction. Lorraine Kuun, July 2011

93.  Fertilisation is internal.  Extra-embryonic (not part of embryo) membranes only develop after fertilisation.  Membranes are: 1. Amnion 2. Allantois 3. Yolk sac 4. Chorion Major evolutionary development; allowed first reptiles to colonise land! Lorraine Kuun, July 2011

95.  The fluid-filled amnion surrounds and protects the embryo, especially against dehydration and shock.  Allantois acts as reservoir for nitrogenous waste in birds and reptiles.  Yolk sac holds nutritious food for development of embryo.  Chorion surrounds all other membranes: in birds it allows for gaseous exchange; in mammals it forms the placenta (taking over functions of allantois and yolk sac, amongst others (see human reproduction). Lorraine Kuun, July 2011

97.  Any pattern of behaviour in which parent spends time or energy to improve the 1 survival, 2 condition and 3 future reproductive success of offspring.  Care can be given at any stage: 1. Prenatal – guarding eggs, building nests, carrying broods, incubating eggs and placental nourishing. 2. Post-natal – providing food, protecting offspring, teaching offspring. Lorraine Kuun, July 2011

98.  Little or no parental care means a low reproductive effort.  Reproductive energy put into producing masses of eggs.  High mortality rate amongst eggs as well as young.  Few individuals survive to reproductive age.  E.g. Most fish, amphibians, insects, most reptiles Lorraine Kuun, July 2011

99.  Few eggs or young produced.  Low mortality rate amongst eggs or young.  High reproductive effort.  Reproductive energy goes into parental care after birth (post-natal).  Most offspring survive to reproductive age.  E.g. Mammals, birds, some reptiles, exceptions amongst fish and Arthropods. Lorraine Kuun, July 2011

100. Left: Midwife toad Right: chicken laying egg, mother feeding young

101. Lorraine Kuun, July 2011 Ovovivipary type of parental care Left: Male seahorse with young emerging from breeding pouch

102. Lorraine Kuun, July 2011