Zoogeography FAS 1450 Fall 2009. Zoogeography - the study of the distributions of animal taxa over the surface of the earth.

Zoogeography

FAS 1450

Fall 2009

Zoogeography - the study of the distributions of animal taxa over

the surface of the earth

Fish Fauna of the Great Lakes

1. Who are they?2. Where did they come from?3. What is the nature of the interactions among species?

1. Who are they? - How many are there? Low diversity:

– Native: 157 species– Introduced: 22 species– TOTAL: 179 species

Comparison with other fish faunas

Laurentian Great Lakes: 179 species Coral Reefs: > 150 on 1 coral head Mississippi River Basin:> 330 species Amazon River Basin: > 2,000 species African Great Lakes: > 450 species

ENDEMIC in one lake!

Why is diversity low?

Temperature

Why is diversity low?

Temperature

Productivity

Why is diversity low?

Temperature

Productivity

Age

Why is diversity low?

Temperature

Productivity

Age

Connections - to other lake and river

basins

1. Who are they? - Two ecological groupings: Coldwater, deep

lake group: Coolwater,

shallow basin group:

1. Who are they? - Two ecological groupings: Coldwater, deep

lake group: lake trout lake whitefish lake herring lake sturgeon deepwater sculpin deepwater ciscos

Coolwater, shallow basin:

1. Who are they? - Two ecological groupings: Coldwater, deep

lake group: lake trout lake whitefish lake herring lake sturgeon deepwater sculpin deepwater ciscos

Coolwater, shallow basin:

yellow perch walleye white bass channel catfish northern pike smallmouth bass

1. Who are they? - A New Group: Introduced species Intentional introductions:

– Common carp, brown trout, steelhead, chinook and coho salmon

Introduced species

Intentional introductions:Common carp, brown trout, steelhead, chinook and coho salmon

Accidental introductions:Alewife, sea lamprey, white perch, pink salmon, rainbow smelt, round goby, ruffe

2. Where did the native species come from?

Endemic species

Immigrant species

2. Where did the native species come from?

Endemic species– species evolved in the system and are

unique to the system:• Blue pike (walleye subspecies)• Deepwater ciscos

2. Where did the native species come from? Immigrant Species:

– species that evolved elsewhere and entered the system from other watersheds:• Mississippi Basin: 79% of fauna• Atlantic drainages: 9% of fauna• Both: 12% of fauna

3. What is the nature of the interactions among species? Predator-Prey relations Niche partitioning (generalists vs.

specialists) Resilient species (to heavy fishing

pressure or predation pressure) Sensitive species (to heavy fishing

pressure or predation pressure)

3. What is the nature of the interactions among species? Effects of introduced species:

– sea lamprey

• Parasites on large fish - lake trout are small

compared with their ocean hosts

• Cause high mortality on lake trout

• Best opportunity for control is in reproductive

and larval stages - concentrated in rivers

3. What is the nature of the interactions among species? Effects of introduced species:

– rainbow smelt and alewife -

planktivores

• compete with native planktivores

• prey on larvae of native fish species

• prey on and compete with each other!

3. What is the nature of the interactions among species? Effects of introduced species:

– gobies & ruffe - benthic fishes

• new immigrants to system

• ballast water introductions of 1980’s

• potential to be competitors and predators

on benthic fishes and invertebrates

Zoogeography of Marine Fishes

Ch. 26 in Moyle & Cech

Barriers to Dispersal in Marine Systems Continents - e.g. Atlantic vs. Pacific faunas Temperature - e.g. tropical vs. temperate vs.

polar Salinity - e.g. estuaries, freshwater (Panama

Canal) Depth - deep-dwelling fishes can be

isolated by submerged mountain ranges

Mechanisms for Dispersal in Marine Fishes Directed movements (e.g., with changes in

temperature; migrations)

Pelagic eggs/larvae - current-born dispersal

Human action - transplants (e.g., striped bass, American shad in Pacific Ocean; 250 species introduced into San Francisco Bay)

Zoogeographic Groupings of Marine Fishes Continental Shelf (neritic) -

– 45% of all fishes– Tropical Zone– Temperate (North & South) Zones– Arctic/Antarctic Zones

Pelagic Abyssal

Zoogeographic Groupings of Marine Fishes Pelagic -

– Epipelagic (1.3% of all fish species)– Meso- & Bathypelagic (5% of all fish species)– Arctic– Temperate– Subtropical– Tropical

Zoogeographic Groupings of Marine Fishes Continental Shelf (neritic) Pelagic Deep benthic (abyssal)

– 6.5% of all fish species– little known about these

Example: Distribution of pelagic piscivores in north Pacific Ocean Arctic:

– Arctic char, pink salmon, some cods– distributed north of 0° isotherm

North Temperate: North Subtropical: Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean Arctic: North Temperate:

– coho, chinook, steelhead, sockeye, chum salmon

– north of 14° isotherm, south of 0° isotherm

North Subtropical: Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean Arctic: North Temperate: North Subtropical:

– some tunas, marlins, basking sharks, mackerel sharks

– north of 20° isotherm, south of 14° isotherm

Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean Arctic: North Temperate: North Subtropical: Tropical:

– flying fish, tunas, whale sharks, marlins– south of 20° isotherm in northern hemisphere

and north of 20° isotherm in southern hemisphere

Ecology of Coral Reef Fishes

Chapter 33

Moyle & Cech

Distribution of Coral Reef Ecosystems Found in Tropical and subtropical oceans

– Mean annual temperature > 20 C– Influenced by currents

• e.g., Gulf Stream brings warm Caribbean water to mid-Atlantic

• corals and coral reef fishes are found as far north as Bermuda (32° North)

Diversity of fish assemblages in Coral Reef Ecosystems Indo-West Pacific: 3000 species

– Great Barrier Reef: 1200 species

Western Atlantic & Caribbean:– 1200 species

Eastern Pacific: < 800 species Eastern Atlantic: < 500 species

Diversity of fish assemblages in Coral Reef Ecosystems Western Atlantic & Caribbean:

– 1200 species– Bahamas: 560 species– San Salvador Island, Bahamas: 300 - 400

species– Dump Reef, San Salvador Island, Bahamas:

> 120 species

How did diversity originate?

Uncertain, but these factors probably important:– Time: long evolutionary record of coral reef

systems– Productivity: high!!– Temperature: rapid growth rates, short

generation times of coral reef systems

How did diversity originate?

Probable important factors, cont.:– Complexity: highly complex physical structure

of reef– Size: small size of many species (highest

diversity in the gobies and blennies - many < 50 mm at maturity

– Niche specialization: high degree of specificity to habitat and diet

– Mechanisms of isolation?

How does diversity persist?(how do so many species get along with out competitive exclusion kicking in?)

Competition hypothesis:– all species are specialists resulting from past

competition - suggests equilibrium (saturation) state

Recruitment limitation hypothesis:

Predation hypothesis:

How does diversity persist?(how do so many species get along with out competitive exclusion kicking in?)

Competition hypothesis:

Recruitment limitation hypothesis:– resources are not limiting, survival to

settlement is limited, chance of settlement is rare and random - “lottery” hypothesis

Predation hypothesis:

How does diversity persist?(how do so many species get along with out competitive exclusion kicking in?)

Competition hypothesis:

Recruitment limitation hypothesis:

Predation hypothesis:– Predation intensity is high on young fish, few

survive to colonize, resulting in random species assemblages

Zoogeography of Freshwater Fishes

Overview

Unique aspects of piscine zoogeography:– longer period of record (since 350 mybp)– constraints to dispersal in aquatic habitats (land

masses)– unique dispersal mechanisms - current

movement of planktonic eggs & larvae

Interpretation of distribution patterns requires: Ecological information - e.g., can the fish

taxa tolerate exposure to fresh water or salt water– freshwater dispersants - e.g., minnows - cannot

tolerate any salinity– Saltwater dispersants - freshwater fishes that

can tolerate salinity - e.g., cichlids

Interpretation of distribution patterns requires: Geological information - what have been

the past connections between water bodies– past and present watershed configurations

important - e.g. previous connections between Great Lakes basin and Mississippi River - 79% of fishes in GL Basin originated from Mississippi basin

Interpretation of distribution patterns requires: Geological information - continental drift

– a single continent (Pangaea) existed as recently as Triassic (200 mybp)

– Pangaea split into two continents at end of Triassic (180 mybp):

• Northern continent - Laurasia (modern Eurasia & North America

• Southern continent - Gondwana (modern Africa, South America, Australia, Antarctica, India)

Interpretation of distribution patterns requires: Geological information - continental drift

– Gondwana split in Jurassic & Cretaceous• Australia broke off first

• South America broke off later

– Several fish taxa are present only on southern continents:

• lungfishes - Australia, S. America, Africa

• cichlids - S. America, Africa, India

• characins - S. America, Africa

Interpretation of distribution patterns requires: Geological information - continental drift

– Laurasia split in Jurassic (120 mybp)• North America separated from Eurasia

– Several fish taxa are present only on northern continents:

• Cyprinids (also have moved into Africa recently)

• Percids - Holarctic (in N. America & Eurasia)

• Catostomids - Nearctic (largely in N. America)

• Centrarchids - Nearctic (only in N. America)

• Cobitids - Palearctic (only in Eurasia)

Mississippi Basin Fauna illustrates these patterns well Contains ~ 330 species, 13 families Basin is ancient - present arrangement since

Rocky Mtns. formed in Tertiary (~65 mybp) Ancient relics are extant today - have benefited

from persistence of the basin:– Chondrosteans - sturgeons, paddlefish– gars, bowfins– mooneyes, pirate perch, cavefishes - only found here

Mississippi Basin Fauna illustrates these patterns well New taxa originated and/or flourished here:

– Notropis/Cyprinella minnows (shiners)– Etheostoma/Percina percids (darters)– ictalurids (catfishes), especially Noturus -

madtoms– centrarchids, especially Lepomis (sunfishes)– catostomids, especially Moxostoma (redhorses)

Why is the Mississippi fauna so diverse?

Provided a refuge from glaciers, due to north-south axis - taxa could retreat south as glaciers moved south

Why is the Mississippi fauna so diverse? Provides a diversity of habitats:

– Different stream types:• Coastal plain (Gulf of Mexico margin)

• Interior highlands– Ozarks

– Tennessee/Kentucky plateau

• Interior lowlands– Western (Missouri River basin)

– Central (Upper Mississippi River basin)

– Eastern (Ohio River basin)

Why is the Mississippi fauna so diverse? Provides a diversity of habitats:

– Speciation requires isolation - offered by these diverse AND separated habitat types

• e.g., Ozark fauna is unique from the Tennessee/Kentucky fauna, even though the habitats are similar - the Mississippi River valley separates them - no passage possible between for small taxa like darters, minnows, madtoms

Why is the Mississippi fauna so diverse? Provides a diversity of habitats:

– Species dependent on small, headwater streams are more easily isolated, and therefore are the most diverse groups

• shiners

• darters

• madtoms