From Diversification to Reproductive Isolation: A Marine Fish Example Maren Wellenreuther and Kendall Clements University of Auckland New Zealand Speciation in the sea… There is now abundant evidence that ecological selection can play an important role in both character divergence and reproductive isolation The vast majority of examples come from terrestrial and lacustrine systems Few studies have investigated whether the same processes are involved in the diversification of marine fishes Structure of this talk 1. Triplefin fishes 2. What are the traits under selection? • Diet choice • Habitat use 3. What are the traits that are potentially available for the development of assortative mating? • Spatial isolation in breeding habitat • Temporal isolation in breeding habitat • Male body colouration 4. Conclusions Model system: NZ triplefin fishes Triplefins are small blennioid fishes that are found in temperate, subtropical and tropical regions 60 mm NZ endemic triplefin fauna is the most diverse in the world 26 species in 14 genera, this is 1/6th of the worlds known species Notoclinops segmentatus What are the mechanisms behind this diversity? Phylogeny 100 100 86 3 species have restricted distributions 23 species sympatric New Zealand 100 95 100 100 100 57 51 100 89 35° 100 100 100 100 97 97 100 83 100 100 78 100 78 89 100 65 100 100 100 49° 100 100 58 75 100 100 NZ species non-NZ species outgroups 100 100 100 100 92 Forsterygion lapillum Grahamina nigripenne Forsterygion varium Grahamina gymnota Grahamina capito A Grahamina capito B Forsterygion flavonigrum Forsterygion malcolmi Obliquichthys maryannae Notoclinops segmentatus Notoclinops yaldwyni Notoclinops caerulepunctus Karalepis stewarti Bellapiscis lesleyae Bellapiscis medius Cryptichthys jojettae Blennodon dorsale Matanui bathytaton Matanui profundum Gilloblennius tripennis Gilloblennius abditus Ruanoho decemdigitatus Ruanoho whero Helcogramma springeri Ucla xenogrammus Helcogramma obtusirostre Enneapterygius abeli Enneapterygius atrogulare Enneapterygius kermadecensis Tripterygion tripteronotus Tripterygion Ibiza Tripterygion delaisi Ceratobregma acanthops Cremnochorites capensis Norfolkia clarkei Trianectes bucephalus Brachynectes fasciatus Apopterygion oculus Lepidoblennius haplodactylus Notoclinus compressus Notoclinus fenestratus Helcogrammoides chilensis Lepidonectes clarkhubbsi Axoclinus lucillae Crocodilichthys gracilis Enneanectes carminalis Ericentrus rubrus (Clinidae) Ecsenius bicolor (Blenniidae) Structure of this talk 1. Triplefin fishes 2. What are the traits under selection? • Diet choice • Habitat use 3. What are the traits that are potentially available for the development of assortative mating? • Spatial isolation in breeding habitat • Temporal isolation in breeding habitat • Male body colouration 4. Conclusions Evidence for trophic partitioning? The majority of NZ triplefin fishes • are generalist carnivorous that feed on invertebrates and • show little specialisation in jaw morphology Two exceptions Blennodon dorsale •Diet consists of mussels Blennodon dorsale Obliquichthys maryannae •Is a semi-pelagic planktivore (Feary and Clements in preparation) Obliquichthys maryannae But they occupy diverse habitats... rockpools rocky reefs deep shelf <500m seaweed estuaries harbours & bays Habitat assessment Sampling sites in NZ 35° Species were sampled throughout their environmental and latitudinal range Habitat use of over 15,000 individual fish was recorded quantitatively Habitat variables (1*1m) • • • • • • • • • Fiordland, Crocket Arm Depth Exposure Rock Cobble Gravel Sand Mud Macroalgae Coralline & turfing algae 49° 3-d MDS plot No strong association between sister species pairs and position in space Species similarity in habitat use Stress = 0.14 For details see: Wellenreuther, Barrett and Clements in press. Marine Ecology Progress Series Bayesian analyses k (tempo of trait evolution): 0.1, evolution has not proceeded in a gradual manner but in rapid bursts λ (phylogenetic signal): 0.05, related taxa are not more similar in habitat use than expected by chance 17 NZ species (genetic data from Hickey), BayesPhylogenies (Pagel & Meade 2004), GTR + G model with reversible jump option; BayesContinuous (Pagel, Meade & Barker 2004) Structure of this talk 1. Triplefin fishes 2. What are the traits under selection? • Diet choice • Habitat use 3. What are the traits that are potentially available for the development of assortative mating? • Spatial isolation in breeding habitat • Temporal isolation in breeding habitat • Male body colouration 4. Conclusions Spatial breeding isolation Triplefins are philopatric and mate in the same territory (≈1m2) that they occupy year round Nest variables (15*15cm) •Depth •On- and offshore •Exposure •Exposed and sheltered •Rock •Microposition •Cobble •Gravel •Mud •Sand •Macroalgae Variables •Coralline & turfing algae Depth Exposure Typical triplefin nests eggs attached to rock Forsterygion lapillum Spatial breeding isolation Canonical Discriminant 2 (21.0%) 2 1 O. maryannae R. whero R. Sand decemdigitatus CobbleGravel F. lapillum US 0 Depth Exposure Coralline Offshore Rock Ecklonia F. flavonigrum SID Carpophyllum F. malcolmi varium TOP Exposed nest position F. -1 G. capito -2 MUD G. nigripenne -3 -3 -2 -1 0 1 2 Canonical Discriminant 1 (61.3%) 3 4 Temporal breeding isolation Spawning periods of triplefin species in NZ Species Jan Feb Mar Apr May F. flavonigrum F. lapillum ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ F. malcolmi F. varium Jun Jul Aug Sept Oct Nov Dec ■ ■ G. capito ■ G. nigripenne ■ ■ ■ ■ ■ O. maryannae R. decemdigitatus R. whero ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ ■ Male body colouration Males of all NZ triplefin species assume a breeding colouration Points measured Measurements of colour intensity were done in ImageJ Male body colouration Example: Ruanoho whero All points are significantly different at p≥0.05 120 Not-spawning Not-spawning (n=11) Intensity of colour 100 80 60 Spawning 40 20 0 1 2 3 4 5 6 Points measured Spawning (n=5) 7 8 9 10 Male body colouration Example: Ruanoho decemdigitatus All points are significantly different at p≥0.05 Not-spawning 120 Not-spawning (n=10) Intensity of colouration 100 80 60 Spawning 40 20 0 1 2 3 4 5 6 Points measured Spawning (n=2) 7 8 9 10 Male body colouration Other species darken on part of the body (e.g. the head) coupled with an increase in colour intensity elsewhere Example: Forsterygion flavonigrum Point 1-2 and 4-10 are significantly different at p≥0.05 140 Not-spawning (n=11) Intensity of colouration 120 100 80 60 40 20 0 1 2 3 4 5 6 Points measured Spawning (n=11) 7 8 9 10 Summary of results 1. What are the traits under selection? Diet choice no Habitat use yes 2. What are the traits that are potentially available for the development of assortative mating? Temporal isolation in breeding times Male breeding colouration Spatial isolation in breeding habitat no little yes Some tentative conclusions... Given that triplefin fishes occur sympatrically around coastal NZ and that there is no geographic evidence for a vicariant barrier to gene flow it seems likely that selection of alternative habitats was involved in the diversification of this group Thanks to… The Ecology, Evolution and Behavior Lab This work was made possible with a Top Achiever Doctoral Scholarship (Research, Science & Technology) and a Marsden grant from the Royal Society of NZ Evidence for UV colouration? UV colouration was investigated in 3 sister species pairs No evidence for any reflectance in the UV spectrum was found for •F. lapillum & G. nigripenne •F. malcolmi & O. maryannae •R. decemdigitatus & R. whero Photographs taken under visible a) and UV light b) a) b) Ruanoho decemdigitatus Ruanoho whero Male body colouration Males turn completely black ? Males turn partially black ? Not known ?
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