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Reproduction in fishes. Reproduction what defines male vs. female?

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Presentation on theme: "Reproduction in fishes. Reproduction what defines male vs. female?"— Presentation transcript:

1 Reproduction in fishes

2 Reproduction what defines male vs. female?

3 Reproduction what defines male vs. female? – reproductive investment sexual strategies: females must be careful in mate selection due to cost

4 Reproduction what defines male vs. female? sexual strategies: females must be careful in mate selection due to cost male investments in reproduction : advertisement, colors, tubercules, kypes, displays nest building, territorial defense parental care, brood guarding

5 Reproduction bioenergetics: C = E + M + G + S + R C – consumption E – excretion M – metabolism G – growth S – storage R – reproduction

6 Reproduction sexual strategies: females must be careful in mate selection due to cost - energy investment in eggs - migration, brooding male investments in reproduction : - advertisement, colors, tubercules, kypes, displays - mate competition - nest building, territorial defense, migration - parental care, brood guarding

7 Anatomy hagfish, lamprey: single gonads no ducts; release gametes into body cavity

8 Anatomy hagfish, lamprey: single gonads no ducts; release gametes into body cavity sharks: paired gonads internal fertilization sperm emitted through cloaca, along grooves in claspers

9 Anatomy hagfish, lamprey: single gonads no ducts; release gametes into body cavity sharks: paired gonads internal fertilization sperm emitted through cloaca, along grooves in claspers chimaeras, bony fishes: paired gonads external and internal fertilization sperm released through separate opening

10 Anatomy hagfish, lamprey: single gonads no ducts; release gametes into body cavity sharks: paired gonads internal fertilization sperm emitted through cloaca, along grooves in claspers chimaeras, bony fishes: paired gonads external and internal fertilization sperm released through separate opening most teleosts: ova maintained in continuous sac from ovary to oviduct exceptions: Salmonidae, Anguillidae, Galaxidae, non-teleosts - these release eggs into body cavity when ripe

11 Anatomy in general: gametes produced only during spawning season gonads reduced during non-reproductive season

12 Timing and location of spawning strategy: avoid competition for spawning habitat maximize access to food for offspring minimize access to offspring by predators

13 Timing and location of spawning strategy: avoid competition for spawning habitat maximize access to food for offspring minimize access to offspring by predators example: Lake Champlain anadromous – salmon catadromous – eels fall spawners – lake trout, whitefish spring spawners – smelt littoral spawners – sculpins, sunfishes, basses stream spawners – suckers, darters, minnows, sturgeon pelagic eggs – burbot

14 Reproduction fecundity egg size and number inversely related egg number directly related to female size (within species) related to food supply, competition = population-regulating mechanism

15 Reproduction fecundity fractional spawners – produce eggs continuously, spawn frequently batch spawners – single reproductive season release all eggs in a short period

16 Reproduction onset of reproduction males typically mature earlier and smaller than females mature earlier if survival and growth are low stable environment – delayed reproduction

17 Reproduction onset of reproduction males typically mature earlier and smaller than females mature earlier if survival and growth are low stable environment – delayed reproduction survivorship high if egg production is low, and vice versa high fecundity fish respond more rapidly to change

18 Reproduction frequency of reproduction semelparity - spawn and then die - huge investment in egg production iteroparity - repeated reproduction allows compensation for a bad year more common in more unstable environments may not spawn every year (sturgeon)

19 Reproductive strategies fertilization external except livebearers (elasmobranches, Poecilidae, etc) mass spawning events (Clupeiformes, smelt, etc.) several males to each female (Salmoniformes, lampreys) several females to each male (Gobiidae) single-pair matings (guppies)

20 Reproductive strategies non-guarders - pelagic (broadcast) spawners semi-buoyant eggs high fecundity egg and larval migrations

21 Reproductive strategies non-guarders - pelagic (broadcast) spawners - benthic spawners on coarse substrates (lake trout) on vegetation (carp, perch) on fine substrates (smelt)

22 Reproductive strategies non-guarders - pelagic (broadcast) spawners - benthic spawners - brood hiders build redd on coarse substrates (salmon, lamprey) credit: Thomas B. Dunklin

23 Reproductive strategies non-guarders - pelagic (broadcast) spawners - benthic spawners - brood hiders build redd on coarse substrates (salmon, lamprey) beach spawners (grunion) use another species (bitterling)

24 Reproductive strategies guarders - nest builders (largemouth bass)

25 Reproductive strategies guarders - nest builders (largemouth bass) rock and gravel (like a lentic redd - sunfishes) plant material (sticklebacks) holes, crevices, cavities (gobies, sculpin, blennies) froth (bettas) anemones (clown fish)

26 Reproductive strategies Bearers - carry eggs and/or fry with them

27 Reproductive strategies Bearers - external bearers transfer: Gasterosteidae, Sygnathidae (pipefishes, seahorses) grade from attachment to skin, to open pouch, to closed pouch gill chambers, forehead obstetrical catfish carry eggs on ventral surface

28 Reproductive strategies Bearers - external bearers mouth: males or females some cichlids and bonytongues

29 Reproductive strategies Bearers - external bearers - internal bearers (viviparity) facultative - killifishes obligate - Lake Baikal sculpins, marine rockfishes (Scorpaenidae) livebearers - Poeciliids, many sharks gradient of nutrient supply from mother superfetation placental viviparity - sharks

30 Reproductive strategies the other extreme: minimal male investment Lophiiformes: deepsea anglerfishes

31 Alternative reproductive strategies sexual vs asexual – pros and cons

32 Alternative reproductive strategies Hermaphroditism synchronous (or simultaneous) hermaphrodites Myctophiformes: (laternfishes) - several families Atheriniformes: Aplocheilidae, Poeciliidae Perciformes: Serranidae (sea basses, hamlets), Labridae (wrasses), and others "Egg-trading" in black hamlets Hypoplectrus nigricans (serranid)

33 Alternative reproductive strategies Hermaphroditism consecutive (sequential) hermaphrodites first male (protandrous) – less common Stomiiformes (lightfish, dragonfish) Scorpaeniformes: Platycephalidae Perciformes: Serranidae, Labridae, and others blue-headed wrasse

34 Alternative reproductive strategies Hermaphroditism consecutive (sequential) hermaphrodites first male (protandrous) – less common first female (protogynous) Synbranchiformes (swamp eels – only freshwater example) Perciformes: Serranidae, Maenidae, Labridae from 100% female -> 100% male from 100% female -> 50% male / 50% female some do not pass thru a female stage ("primary males")

35 Alternative reproductive strategies Unisexual species processes of DNA re-assortment in sexual species: 1. crossing-over during first meiotic division 2. random segregation of chromosomes in second meiotic division 3. addition of male and female chromosomes after fertilization

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37 Alternative reproductive strategies parthenogenesis: females produce diploid eggs, no sperm used premeiotic endomitosis - mitotic division without cytokinesis

38 Alternative reproductive strategies parthenogenesis: females produce diploid eggs, no sperm used premeiotic endomitosis - mitotic division without cytokinesis gynogenesis: females produce diploid eggs, use sperm to stimulate development male genome not used congeneric species are used for sperm example: Poecilia formosa (Amazon molly)

39 Alternative reproductive strategies parthenogenesis: females produce diploid eggs, no sperm used premeiotic endomitosis - mitotic division without cytokinesis gynogenesis: females produce diploid eggs, use sperm to stimulate development male genome not used congeneric species are used for sperm androgenesis – does not exist (why?)

40 Alternative reproductive strategies parthenogenesis: females produce diploid eggs, no sperm used premeiotic endomitosis - mitotic division without cytokinesis gynogenesis: females produce diploid eggs, use sperm to stimulate development male genome not used congeneric species are used for sperm hybridogenesis: one genome from female in egg, male genome discarded - then uses sperm to restore ploidy - no crossing over example: Poeciliopsis monacha-lucida

41 Alternative reproductive strategies Alternative male strategies - jacks (salmon and trout)

42 Alternative reproductive strategies Alternative male strategies - jacks (salmon and trout) - sneakers (SFs) in bluegills, wrasses, sunfishes evolutionarily stable strategy - if small, become SF, avoid stress of being parental male

43 Alternative reproductive strategies Alternative male strategies - jacks (salmon and trout) - sneakers (SFs) in bluegills, wrasses, sunfishes evolutionarily stable strategy - if small, become SF, avoid stress of being parental male - satellite males (mimic females) in bluegills, hover near nest

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45 DEVELOPMENT

46 Developmental stages egg <0.5 mm - 10 cm variable shape, attachments variable buoyancy water hardening yellow perch egg mass round goby (0.5 mm) lake trout (5 mm) skate (5 cm)

47 Developmental stages egg embryo - dependent on mother or yolk sac for food (free embryo) Credit: Fly Anglers online Susan Middleton & David Liittschwager

48 Developmental stages egg embryo - dependent on mother or yolk sac for food (free embryo) larvae - not fully functional, may look totally unlike adult ends when axial skeleton is formed

49 Developmental stages egg embryo - dependent on mother or yolk sac for food (free embryo) larvae - not fully functional, may look totally unlike adult ends when axial skeleton is formed juvenile - small functional individual, immature adult - reproductively mature

50 Developmental stages egg embryo - dependent on mother or yolk sac for food (free embryo) larvae - not fully functional, may look totally unlike adult ends when axial skeleton is formed juvenile - small functional individual, immature adult - reproductively mature Credit: USFWS, GLFC

51 indirect development (perch) - larval stages go through trophic phases different from adults intermediate (salmonids) - embryonic stage with yolk; virtually no larval stage direct development (gobies) - juvenile is fully functional miniature of adults (no larval stage)

52 Genetics

53 Sex determination heterogametic sex can be male or female Genetics

54 Sex determination heterogametic sex can be male or female Polyploidy - more than two sets of chromosomes critical difference between odd and even sets Genetics

55 Sex determination heterogametic sex can be male or female Polyploidy - more than two sets of chromosomes critical difference between odd and even sets - use of triploid grass carp Genetics http://www.bajthomas.btinternet.co.uk

56 Natural polyploids triploids - Cyprinidontiformes: Poeciliid triploids - different solutions to the problem of triploid gametes…. Genetics

57 Natural polyploids triploids - Cyprinidontiformes: Poeciliid triploids tetraploids (autotetraploids vs. allotetraploids) Acipenseriformes (sturgeons and paddlefish) Salmonidae (all trouts - autotetraploid) ancestral chromosome doubling event Cypriniformes some cyprinids all catostomids are allotetraploid Siluriformes Corydoras catfishes Perciformes Only Lucioperca sandra: 2n = 24 in Sweden but 2n = 48 in Finland Genetics

58 Natural polyploids triploids - Cyprinidontiformes: Poeciliid triploids tetraploids (autotetraploids vs. allotetraploids) hexaploids and octaploids (rare in carp) Genetics

59 Natural hybrids salmonids centrarchids Genetics


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