Date of Award


Document type


Access Type

Open Access Dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program


First Advisor

Michael F. Dolan

Second Advisor

Richard W. Wilkie

Third Advisor

Elizabeth R. Dumont

Subject Categories

Earth Sciences


The origin and geographical distribution of mammalian species (my examples are lemurs and bats) correlate with predictable chromosomal structural changes (KFT=karyotypic fission theory). Chromosome studies provide information about fertility between individuals and they are significant for identification of the geographical origin of reproductive isolation within mammal families. Each family predictably has chromosome sets with numbers that range from one to double the lowest number of chromosomes. The chromosome numbers of all species within a single family are used to reconstruct that family’s evolutionary geographical dispersion. Polymorphic chromosome numbers (that is a range such as 34, 35, 36, 37, and 38) in a single population indicate the location where chromosomal diversification arose. Chromosome numbers of descending order correlate with relative distance from fission epicenters as the fissioned chromosomes gradually spread to neighboring populations. Furthermore, the location of chromosomal diversification (that is “karyotypic fission events) is associated with geographical “zones of transition” (after Professor R.W. Wilkie). My analysis, mapped one (Lepilemuridae) of the five families of lemurs (Class Mammalia, Order Primates, sub-order Lemuridae). The origin of this family’s diversification is here hypothesized to have occurred at an ecological transition zone in Northern Madagascar between a humid evergreen-forest that extends to the East relative to a dry deciduous forest along the West Coast. My analysis of Vespertilionidae (insectivorous bats representing one third of all bat species) suggests a diversification event occurred in Asia; South China.

Geographical distribution is important in the formation of biological diversity. A single species can inhabit a wide range and exhibit great diversity that is brought about by natural selection. The Holarctic reindeer found in Scandinavia, Russia, China, Canada and Alaska (including caribou) are all a single species Rangifertarandus that exhibits variation in size and in coat pattern, changes brought about by adaptive selection by the environment or human selective breeding but they all have 70 similar chromosomes and they are all reproductively compatible. There is a single species of reindeer. Although, there is measurable DNA sequence divergence; there has been no “speciation” as these circumpolar cervids are genetically compatible.