Vertebrate Zoogeography Introduction

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Chapter 3

Vertebrate Zoogeography


Zoogeography is the study of the geographic distribution of animals and how they (animals and environment) mutually influence each other

This will require a good knowledge of historical changes in climate, geography, geomorphology, and species distribution
Faunal Zoogeography relates faunal lists to specific areas

It is the basis of all zoogeographic research

Comparative Zoogeography uses specific features and classify distributions

When comparing faunal assemblages from different areas, distributions may not be consistent with present geological and geographical ranges

With some exception, most of the animals are not cosmopolitan in distribution. The wide majority are limited to a particular region

When the limiting factors are many and specific, we are talking about a Narrowly endemic species (or group of species)

Giant panda (Ailuropoda melanoleuca) bamboo forests in China

Tuataras (Sphenodon spp) islands on the coast of New Zealand

The distribution of a vertebrate species can be expressed as
1- its current Geographic range
2- its Geologic range
3- its Ecological distribution
1- Geographic range: land and/or water area where the sp currently occur

Disjunct distribution: Camelidae (Asia –camels and South America – llamas and other spp)

2- Geologic range: taxon’s past and present distribution in time
3- Ecological distribution: its distribution in relation with the communities where that sp belongs
Closely related spp – adjacent ranges
Center of distribution and center of speciation: areas from which the current related spp evolve from their common ancestral form
What factors will affect the sp distribution?
1- means of dispersal

2- barriers to such dispersal

Barriers are relative
Three types:
1- Physical barriers

2- Climatic barriers

3- Biological barriers
1- Physical barriers: land, water, elevation soil type, topography, special cases (roads for some small mammals)
2- Climatic barriers: temperature, humidity, rainfall, sunlight
3- Biological barriers: lack of food, presence of predator or competitor
Land bridges between North America and Eurasia, North America and South America, Mozambique and Madagascar
A particularly well documented case, the migration of marsupials from South America to Antarctica to Australia, where they went through an extensive adaptive radiation without competition from placental mammals
Historical Zoogeography: attempt to provide explanations of spatial and temporal distributions based on past events
Ecological Zoogeography: deals with present events and how those events condition relationships at the community level
Distribution in time depends on continuing its reproductive potential
Distribution in space deals with the potential of a sp to move and occupy suitable areas, always considering factors such as geography, geology, climate, ecology, and human activity
Geographic Distribution: A.R. Wallace recognized that most taxa have congruent distributions

He divided (based on affinities between terrestrial fauna and flora) the land masses into six biogeographic regions, characterizing each region with a specific faunal assemblage

Holarctic Region (Palearctic + Nearctic)

Oriental Region


Ethiopian Region

Australian Region

Holarctic Region (Palearctic + Nearctic)

Northern hemisphere (old and new world)

Palearctic Region: Europe & Asia

Nearctic Region: North America to central Mexico

Both regions imply circumpolar distribution, as with the Snowy owls (Nyctea scandiaca), Arctic foxes (Alopex lagopus), and Polar bears (Ursus maritimus), among others
Oriental Region: Asia south of the Himalayas (India, southeast Asia, Indonesia, Philippines). Unique spp are Indiand & reticulated pythons (Python molurus and P. reticulatus), king cobras (Ophiophagus hannah), gibbons (Hylobates spp), orangutans (Pongo pygmaeus), Indian elephant (Elephas maximus), among others
Neotropical Region: includes central and South America, including the Caribbean islands, a stepping stone-corridor between the neotropical and the nearctic regions. South American lung fish (Lepidosirenidae), poison-dart frogs (Dendrobates & Phyllobates), anacondas (Eunectes murinus), rheas (Rhea sp), toucans (Ramphastidae), South American Camelidae, anteater (Myrmecophaga sp, Tamandua sp & Cyclopes sp), capybaras (Hydrochaeris hydrochaeris), etc.
Ethiopian Region: most of Africa, south of the Sahara desert, with endemics such as Ostriches (Struthio camelus), zebras (Equus spp), gorillas (Gorilla gorilla), aardvarks (Orycteropus afer), hippopotamuses (Hippopotamus amphibius), and the African lung fish (Protopterus sp)
Australian Region: including Autralia, New Zealand, New Guinea, Tasmania and other islands. The Wallace line separate this region from the Oriental. In addition to the most diversely radiated marsupial assemblage, emus (Dromiceius sp) cassowaries (Casuarius sp), platypus (Ornithorhynchus anatinus), echidnas (Tachyglossus sp and Zaglossus sp) inhabit the region. Only two fully freshwater fish species, Australian lung fish (Neoceratodus forsteri) and the barramundi (Scleropages leichardti)
Geological Distribution

Earth was formed 4.6 billion years ago and life started as such at least 3.8 billion years ago. Since then, Earth undergoes geological changes on its crust and inside. The earth crust consist of rigid plates (about 100 km thick) floating on top of a liquid-like mantle. These plates move around (very slowly) and re-arrange its position along faults. Plate tectonics is how we call these movements. The movements of these plates (and the continents) has significantly affected climates, sea levels and therefore the distribution of vertebrates over time

600-400 million years ago (Cambrian to Silurian periods) six continents existed. The plates moved and the continental masses collided to form super continents that then split apart to form new ocean in between
Laurasia (Laurentia + Baltica) was formed between 420-360 mya, and later (360-270 mya) collided with Gondwana to form the “world continent” Pangea
Pangea was not static and drifted northward causing dramatic climatic changes
Between 280-200 mya, higher latitudes were warm and moist, while low and middle latitudes were much drier (regional differences in rainfall). At this time the Appalachian Mountains were formed
By the late Triassic (210 mya) Pangea split into separate continents, forcing the independent development of regional biotas (flora + fauna)
Asia and Africa began separating from each other (early Jurassic - 200 mya). North America began to drift westward (continues today) and away from Africa and South America (although still connected with Europe in the north)
By 100 mya (Jurassic-Cretaceous periods) sea level rises, flooding low-lying areas creating shallow inland seas across North America, Eurasia and Canada. At this time, the Sierra Nevada, Andes, Himalayas and Rocky Mountains were formed, isolating regions and altering climate in vast areas
By the mid to late Cretaceous (80-60 mya) a massive regression of epicontinental seas exposed land and altered climate and therefore biota composition
The Atlantic Ocean is expanding since the early Tertiary (70 mys) to current times due to a continuous westward drift of the Americas and sea levels fluctuations. During the Pliocene (2-5 mya) Central America arose connecting North and South America (which were isolated for many million years). This event produced a phenomenon known as “the great american biotic interchange”
Earth has undergone a series of climatic shifts through time, with periods of rain followed by droughts, cooler temps. alternated with warmer periods
Changes in temps caused changes in sea levels, which in terms caused the formation of filters for dispersals
Glaciations have occurred several times, with the Wisconsin glaciation as the most recent one. These events not only change the sea level but also altered the biotic composition on extensive areas, restricting distributions toward the tropics and in some cases, when glacials receded, producing disjunct distributions and disjunct species
Ecological Distribution

Based on major environmental factors such as water, salinity, humidity, temperature, light, oxygen, pressure and food, vertebrate distribute around the globe

There are three (3) major ecological environments recognized: marine, fresh water and terrestrial

the largest (70% Earth’s surface)

a vast, interconnected mass


temps (-2.2 to 32 ºC, w/local ranger never larger than 5 ºC)

depths (0 to 10.8 km)

salinity (35 ppt)

Photic vs. Aphotic (w/1,000 mts as the recognized limit)

also pressure (increase rate of 1 atmosphere -14.7 lbs/inch²- for every 10 mts depth)
Pelagic -open waters- (neritic + oceanic) & Benthic -ocean floor- regions
Neritic zone: cetaceans (whales, dolphins), reptiles (sea turtles, sea snakes), fish, other mammals (sea otter)
Abyssopelagic zone (3-6 km): Rattails (Macrouridae), brotulas (Ophidiidae), batfishes (Ogcocephalidae); most eel-like, blind, well developed cephalic lateral-line canals and senses of smell and touch
Hadopelagic zone (more than 6 km): deepest living fish known – Abyssobrotula galatheae, lives between 3-8.3 km deep
Fresh Water

the smallest, from rain puddles to lakes and rivers

Lotic (moving) and lentic (still) systems


temps (freezing to boiling)

clear or turbid


salinity (0-0.5 ppt)

depths (0 to 1.7 km or more ?)

pH (CO2, organic acids or pollution)

Lotic environments will present a gradient of variables, from a very rapid flowing bodies, where species such as salmonids present strong lateral muscles, to slow-flowing streams, where bass and sunfishes (Centrarchidae), perches and darters (Percidae), shiners or minnows (Cyprinidae), pikes (Esocidae), and suckers (Catostomidae)
Lentic bodies (lakes, ponds, etc) contain four life zones
Littoral: closer to shore, rooted vegetation

Limnetic: main body of water

Both zones inhabited or used by all classes of vertebrates
In deep lakes, Profundal zone: open water below depth of light penetration (fish adapted to cooler, darker waters & Benthic zone: bottom of the lake (decomposers)
Catadromous: most of their adult lives in freshwaters and return to the sea to reproduce (eels)
Anadromous: most of their adult lives in the ocean and return to the rivers to reproduce (salmons)

the most variable of all 3 environments

elevation (bellow sea level to 8.5 km)

air temps (-60 to 60 ºC, increasing at a rate of 1.2 ºC for every 305 mts in elevation)

pption (from a fraction of a cm to 1.3 mts/year
Based on these variables, there are different ways to classify terrestrial environments: biomes, life zones, and biotic provinces
Biomes: based on natural climaxic communities (Clements & Shelford, 1939)
Tundra: around the Arctic circle (up to 2,000 km south), 20 cm of pption, seasonal photoperiodic fluctuation, permafrost, flowering and fruiting cycles very quick

Permanent residents: lemmings (Lemmus spp, Dicrostonyx spp), ptarmigan (Lagopus sp), musk-ox (Ovibos moschatus), polar bears (Ursus maritimus), caribou (Rangifer tarandus)

Taiga: coniferous forests north of Eurasia and North America (and high elevetions southward), cold winters and short summers, pption .4-1 mt/y (much as snow), growing season of about 130 days, little light reaches the ground

Permanent residents: Snowy owls (Nyctea scandiaca), crossbills (Loxia sp), lynx (Lynx canadensis), wolves (Canis lupus), moose (Alces alces), and bears (Ursus spp)

Temperate Deciduous forests: south of the Taiga (in most cases), dominated by deciduous forests species, four well-defined seasons, a growing season of up to 300 days, pption .75 to 1.5 mts, good amount of light reaches the ground

Permanent residents: certain salamanders (Plethodontidae), skinks (Eumeces spp), garter snakes (Thamnophis spp), turkeys (Meleagris gallopavo), pileated woodpecker (Hylatomus pileatus), squirrels (Sciurus spp), bobcats (Lynx rufus), foxes (Vulpes spp & Urocyon spp), white-tailed deer (Odocoileus virginianus)

Grasslands: enough water for grass but not enough for trees (.2 mts), seasonal droughts and fires, very rich and well-developed soils, called “prairies” (temperate), “savannas” (tropical) or even “mediterranean chaparrals” (rain during winter, resulting a mixture of grass and shrubby scrublands)

Permanent residents: for prairies - other skink spp (Eumeces spp), rattlesnakes (Crotalus spp), burrowing owls (Speotyto cunicularia), prairie dogs (Cynomys spp), coyotes (Canis latrans), bison (Bison bison); for savannas – elephants (Loxodonta africana), giraffes (Giraffa camelopardalis), many other spp of large and medium herbivores, lions (Panthera leo), cheetahs (Acinonyx jubatus), and hyenas (Hyaena spp)

Deserts: larger in Africa, Asia and Australia and smaller in North and South America, hot days and cool nights, less than .25 mt/y, vegetation very sparse, many animal spp are burrowers, common adaptations include reduction of cutaneous glands, concentrated urine, and dry feces, many metabolize water from food and also estivate (inactivity during summer), many rodents from xeric habitats all over the world developed similar suit of characters (morphological, physiological, and ecological convergence)

Permanent residents: Gila monsters (heloderma suspectum), rattlesnakes (Crotalus sp), roadruners (geococcyx californicus), and kangaroo rats (Dipodomys spp)

Tropical Forests: two major types – tropical deciduous forests & tropical rain forests, more than 2.5 mts/y in pption combined with continual warmth (20-25 ºC), makes these the richest biome. With multilayer canopy, epiphytes, lianas, and woody vines and a dense understory. Morphological convergence is strikingly evident between African and South American rain forest’s vertebrates

Permanent residents: treefrogs (Hylidae), tree (or green) iguanas (Iguanidae), caimans (Caiman crocodilus), parrots (Psitacidae), monkeys (Saimiri spp, Cebus spp, Alouatta spp, among others), and jaguars (Panthera onca)

Life Zones: proposed by C. Hart Merriam, based on 1- animals and plants are restricted in northward distribution by the total heat during the growing and reproductive season and 2- animals and plants are restricted in southward distribution by the mean temp of the hottest part of the year
Each zone has a temp range of about 4ºC. Three regions (Boreal, Austral and Tropical) with life zones within
Boreal region: it includes the Arctic-Alpine, Hudsonian, and canadian zones with examples of permanent residents for the Arctic-Alpine zone: arctic foxes (Alopex lagopus), Arctic hares (Lepus arcticus), and lemmings (Lemmus spp and Dicrostonyx spp); for the Hudsonian zone: great gray owls (Strix nebulosa), moose (Alces alces), and wolverine (Gulo gulo); and for the canadian zone: spruce grouse (Canachites canadensis), varying hares (Lepus americanus), and lynx (Lynx canadensis)
Austral region: with also three zones Transitional, Upper and lower zones. Transition zone, with population residents: sage and sharp-tailes grouses (Centrocercus sp & Pedioecetes sp), northern flying squirrels (Glaucomys sabrinus), and black bears (Ursus americanus)

Upper (sonoran) austral zone: eastern wood frogs (Rana sylvatica), cardinals (Richmondena cardinalis), eastern wood rats (Neotoma spp) & ring-tailed cats (Bassariscus astutus), and northern grasshoper mice (Onychomys spp)

Lower (sonoran) austral region: frogs (Rana spp), alligator snapping turtles (Macroclemys temminki), anoles (Anolis spp), brown pelicans (Pelicanus occidentalis), rats (Oryzomys spp, Sigmodon spp) & kit foxes (Vulpes macrotis), kangaroo rats (Dipodomys spp) and pocket mices (Perognathus spp)
Tropical region divided into arid and humid life zones (an oversimplification of a much more complex system)
Biotic Provinces, a third method of classification of North American plants and animals is characterized by important ecological associations (climaxic ecosystems, fauna, climate, physiology and soils) and is based on vegetation types
Biotic provinces are subdivided into biotic districts and “vertical” life belts. Boundaries are physiographical barriers and varies from time to time (ecological successions, climate changes)
Changes (in distribution) caused by human activity

  • Domestication, dogs, cats, cattle, goats, horses, pigs

  • Extinction, introduced predators reduced geographic ranges (to local or complete extinction)

  • Habitat alteration, construction of reservoirs, artificial canals, cutting forests, produces disturbances in nature, helping certain spp to thrive --Coyote (Canis latrans), white-tailed deer (Odocoileus virginianus) and others to disappear --Cougars (Felis concolor) and wolves (Canis lupus and C. rufus)

  • Transport / introductions, european rabbits (Oryctolagus cuniculus), Norway rat (Rattus norvegicus), house mouse (Mus musculus), starlings (Sturnus vulgaris), English house sparrows (Passer domesticus), Mongooses (Herpestes spp), nutria (Myocastor coypu), special note on the accidental releases of hundreds of exotic spp (pet trade) in Florida or successful introductions of spp that benefited environment and economy (ringnecked pheasants (Phasianus colchicus) and eastern gray partridge (Perdix perdix)

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