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 4 Continents - e.g. Atlantic vs. Pacific faunas 4 Temperature - e.g. tropical vs. temperate vs. polar 4 Salinity - e.g. estuaries, freshwater (Panama Canal) 4 Depth - deep-dwelling fishes can be isolated by submerged mountain ranges

Mechanisms for Dispersal in Marine Fishes 4 Directed movements (e.g., with changes in temperature; migrations) 4 Pelagic eggs/larvae - current-born dispersal 4 Human action - transplants (e.g., striped bass, American shad in Pacific Ocean; 250 species introduced into San Francisco Bay)

Zoogeographic Groupings of Marine Fishes 4 Continental Shelf (neritic) - –45% of all fishes –Tropical Zone –Temperate (North & South) Zones –Arctic/Antarctic Zones 4 Pelagic 4 Abyssal

Zoogeographic Groupings of Marine Fishes 4 Pelagic - –Epipelagic (1.3% of all fish species) –Meso- & Bathypelagic (5% of all fish species) –Arctic –Temperate –Subtropical –Tropical

Zoogeographic Groupings of Marine Fishes 4 Continental Shelf (neritic) 4 Pelagic 4 Deep benthic (abyssal) –6.5% of all fish species –little known about these

Example: Distribution of pelagic piscivores in north Pacific Ocean 4 Arctic: –Arctic char, pink salmon, some cods –distributed north of 0° isotherm 4 North Temperate: 4 North Subtropical: 4 Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean 4 Arctic: 4 North Temperate: –coho, chinook, steelhead, sockeye, chum salmon –north of 14° isotherm, south of 0° isotherm 4 North Subtropical: 4 Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean 4 Arctic: 4 North Temperate: 4 North Subtropical: –some tunas, marlins, basking sharks, mackerel sharks –north of 20° isotherm, south of 14° isotherm 4 Tropical:

Example: Distribution of pelagic piscivores in north Pacific Ocean 4 Arctic: 4 North Temperate: 4 North Subtropical: 4 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 4 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 4 Indo-West Pacific: 3000 species –Great Barrier Reef: 1200 species 4 Western Atlantic & Caribbean: –1200 species 4 Eastern Pacific: < 800 species 4 Eastern Atlantic: < 500 species

Diversity of fish assemblages in Coral Reef Ecosystems 4 Western Atlantic & Caribbean: –1200 species –Bahamas: 560 species –San Salvador Island, Bahamas: species –Dump Reef, San Salvador Island, Bahamas: > 120 species

How did diversity originate? 4 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? 4 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?) 4 Competition hypothesis: –all species are specialists resulting from past competition - suggests equilibrium (saturation) state 4 Recruitment limitation hypothesis: 4 Predation hypothesis:

How does diversity persist? (how do so many species get along with out competitive exclusion kicking in?) 4 Competition hypothesis: 4 Recruitment limitation hypothesis: –resources are not limiting, survival to settlement is limited, chance of settlement is rare and random - “lottery” hypothesis 4 Predation hypothesis:

How does diversity persist? (how do so many species get along with out competitive exclusion kicking in?) 4 Competition hypothesis: 4 Recruitment limitation hypothesis: 4 Predation hypothesis: –Predation intensity is high on young fish, few survive to colonize, resulting in random species assemblages

Zoogeography of Freshwater Fishes

Overview 4 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: 4 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: 4 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: 4 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: 4 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: 4 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 4 Contains ~ 330 species, 13 families 4 Basin is ancient - present arrangement since Rocky Mtns. formed in Tertiary (~65 mybp) 4 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 4 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? 4 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? 4 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? 4 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? 4 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