Biodiversity engine for fishes: Shifting water depth

Date:
February 13, 2023
Source:
Yale University
Summary:
Fish, the most biodiverse vertebrates in the animal kingdom,
present evolutionary biologists a conundrum: The greatest species
richness is found in the world's tropical waters, yet the fish
groups that generate new species most rapidly inhabit colder
climates at higher latitudes. A new study helps to explain this
paradox. The researchers discovered that the ability of fish in
temperate and polar ecosystems to transition back and forth from
shallow to deep water triggers species diversification.

Their findings suggest that as climate change warms the oceans at
higher latitudes, it will impede the evolution of fish species.


Facebook Twitter Pinterest LinkedIN Email
FULL STORY ========================================================================== Fish, the most biodiverse vertebrates in the animal kingdom, present evolutionary biologists a conundrum: The greatest species richness is
found in the world's tropical waters, yet the fish groups that generate
new species most rapidly inhabit colder climates at higher latitudes.


==========================================================================
A new Yale study helps to explain this paradox. The researchers
discovered that the ability of fish in temperate and polar ecosystems
to transition back and forth from shallow to deep water triggers species diversification.

Their findings, published Feb. 11 in the journal Nature Communications,
suggest that as climate change warms the oceans at higher latitudes,
it will impede the evolution of fish species.

"The fish clades contributing the most fish diversity in today's oceans
are leveraging the water column and the ocean depths, in particular,
to diversify," said lead author Sarah T. Friedman, who conducted the
research while a G.

Evelyn Hutchinson postdoctoral associate at Yale. "Fishes that make
these forays into the deep ocean are almost exclusively located in
high latitudes, where it's easier to move along the water column. These
regions are experiencing the most drastic warming due to climate change,
which threatens to disrupt speciation by making it more difficult for
fish to change depths." Friedman, now a research fish biologist at the National Oceanic and Atmospheric Administration, coauthored the study
with Martha Mun~oz, an assistant professor of ecology and evolutionary
biology in Yale's Faculty of Arts and Sciences, and an assistant curator
of vertebrate zoology at the Yale Peabody Museum.

For the study, the researchers analyzed existing data on the global
species occurrence of 4,067 fish species that included information on
species geographic range and speciation rate. In part, their analysis
modeled how often fish lineages might be expected to transition
across ocean depths. By laying out a distribution of anticipated
shifts in depth, the researchers could compare the number of observed transitions in specific lineages. They found that species-rich,
high-latitude lineages -- eelpouts, rockfishes, flatfishes, icefishes,
and snailfishes -- transitioned up and down the water column more often
than expected. Meanwhile, hyper-diverse tropical lineages, such as gobies
and wrasses, changed depth less frequently than predicted.

Fish clades, evolutionary lineages that share a common ancestor, that
can freely disperse along the depth gradient may be more likely to
capitalize on novel resources or niches at specific depths and become
isolated from other members of their group, the researchers said. This
can lead to repeated local adaptation and the evolution of new species.

Many variables can affect a fish's ability to move between depths,
including water temperature, pressure, and light penetration. Friedman and Mun~oz suggest that temperature plays an important role in the ability
of high-latitude fish clades to transition along the water column. Fish
clades that inhabit colder water have an easier time traveling into
ocean depths, where water temperature plummets dramatically. By contrast, tropical fish, which spend their lives in warm, shallow waters, face steep thermal barrier to transitioning to the deep ocean, the researchers said.

The existing high biodiversity in tropical waters could be a remnant of
the deep past when warmer regions were hotbeds of species generation,
but over time, most diversification began occurring closer to the Earth's poles, they explained.

But this biodiversity engine at higher latitudes is vulnerable to
climate change. Since the water profile is so much more uniform at
higher latitudes than in the tropics, the fish that inhabit them are physiologically fine-tuned to those environments, Mun~oz explained. For
them, a one-degree shift in temperature will be physiologically more challenging than for an organism that is more of a thermal generalist.

"As the oceans warm, organisms might face steeper barriers to dispersal
across the depth column," Mun~oz said. "Over time, I think we'll see a
slowdown of this engine of biodiversification." The study was funded by
the G. Evelyn Hutchinson Environmental Postdoctoral Fellowship, which
aims to enable creative research collaborations in the environmental
sciences at Yale by developing diverse academic excellence at the
postdoctoral level.

* RELATED_TOPICS
o Plants_&_Animals
# Fish # Marine_Biology # Nature # Fisheries
o Earth_&_Climate
# Water # Environmental_Awareness # Ecology #
Environmental_Issues
* RELATED_TERMS
o Fish o Fishery o Zebrafish o Fish_farming o Cormorant o
Deep_sea_fish o Sei_Whale o Fin_Whale

========================================================================== Story Source: Materials provided by Yale_University. Original written
by Mike Cummings. Note: Content may be edited for style and length.


========================================================================== Journal Reference:
1. Sarah T. Friedman, Martha M. Mun~oz. A latitudinal gradient
of deep-sea
invasions for marine fishes. Nature Communications, 2023; 14 (1)
DOI: 10.1038/s41467-023-36501-4 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2023/02/230213201026.htm

--- up 50 weeks, 10 hours, 50 minutes
* Origin: -=> Castle Rock BBS <=- Now Husky HPT Powered! (1:317/3)