Hot off the press! Out now in Current Biology "Maternal investment evolves with larger body size and higher diversification rate in sharks and rays" Read here: authors.elsevier.com/a/1jCxB3QW8S6E… Massive thanks to my co-authors Matt Pennell Kara Yopak and Nicholas Dulvy

The sequence and drivers of the evolution of live-bearing and matrotrophy are fundamental questions in vertebrate macroecology, and sharks and rays with their reproductive diversity (everything from egg-laying to placentas) are an ideal group for addressing these questions.

Egg-laying is ancestral and live-bearing and matrotrophy (additional maternal nourishment beyond the initial yolk) have evolved multiple times. While some groups are invariant (all skates lay eggs), groups like the requiem sharks exhibit diverse reproductive modes and habitats

Understanding repro mode evolution in sharks and rays we can test different theories about how these traits relate to diversification dynamics (i.e. rates of speciation and extinction): the Viviparity Driven Conflict Hypothesis and the Novel Ecological Opportunity hypothesis.

While teleosts have demonstrated increased speciation with sexual selection, the highest rates of speciation were seen in Skates (Rajiformes) and Neotropical Freshwater Rays (Potamotrygonidae) which highlight the colonization of novel habitats.

Rachel getting ready for her 2nd round of measuring rays! This time at UBC’s Beaty Biodiversity Museum 🐳 - looking forward to pulling these little guys out in July #dulvylabgoesoutside #raysnearme #sharksnearme

Okay so today we got to see the BIG tanks SAIAB and found the Reef Manta Ray Mobula alfredi; the #hottake was that this was just gills-on-fins... look at the length of those gill slits... #MetabolicMorphology

Phew! after 2 weeks working SAIAB its a wrap. We measured 25+ #MetabolicMorphology traits from 43 sharks & 240 ray specimens, spanning 60 species, from endemic catsharks, skates & electric rays to pelagic and deepsea sharks. The Coelocanth was discovered in East London by

New #GlobalSharkTrends study published in Science Magazine reveals that #overfishing has more than halved shark & ray populations over the past 50-years causing widespread erosion of ecological function and exceptionally high extinction risk 👉🏽Full article bit.ly/GlobalSharkTre…

New #GlobalSharkTrends analysis funded by Shark Conservation Fund serves as a #wakeupcall for urgent action to turn the tide for these extraordinary animals: bit.ly/GlobalSharkTre… 🧵2/20 #EndOverfishing #SustainableDevelopmentGoals

Overfishing has halved populations of the chondrichthyan fishes – sharks, rays, and chimaeras – since 1970. Target fisheries and incidental capture (bycatch), in particular, has resulted in over one-third threatened with extinction. #GlobalSharkTrends 🧵4/20 #EndOverfishing

The Red List Index (RLI) is based on the @IUCNSSC IUCN SSC Marine Conservation Committee -on BlueSky IUCN Red List assessments and is widely used to report on the status of terrestrial biodiversity and the effectiveness of conservation actions, yet there is no equivalent for the oceans #GlobalSharkTrends

#GlobalSharkTrends Since we wrote the paper Colin Simpfendorfer coded a mesmerizing GIF of the Red List Index for sharks, rays & chimaeras 🧵7/20

#GlobalSharkTrends Here is another Colin Simpfendorfer GIF of Shark & Ray Red List Index by habitat 🧵8/20

Researchers highlight troubling dark spots where shark & ray biodiversity is plummeting, w/ 👉 steep declines in RLI 👉 high richness & endemicity: 1. Japan–Taiwan 2. Indonesia to New Guinea 3. India & Bay of Bengal 4. Western Indian Ocean 5. SW Atlantic 6. Galapagos & SE Pacific

Bright spots with some science-based fisheries management measure benefiting sharks & rays: 1. USA & Canada 2. NE Atlantic 3. S. Africa 4. Australia & New Zealand #OceanOptimism 🧵15/20

Brightspot countries for shark and ray conservation have: 👉 high catch-per-unit-effort 👉 fisheries subsidies that do not promote overfishing 👉 stronger governance science.org/doi/10.1126/sc… #OceanOptimism 17/20

We urge the adoption of the Shark & Ray Red List Index to track progress on ocean conservation goals, like the Global #Biodiversity Framework Target 5 and #SustainableDevelopmentGoal 14.4. Accountability is key for preserving marine life! science.org/doi/10.1126/sc… 🧵20/20 🦈