Implications of the superspecies concept to insular avifauna and conservation priorities in the Philippines

Professorial Chair Lecture

Metro Manila Commission Professorial Chair Lecture

Place

New CAS Auditorium, UPLB

Date

6-26-2006

Abstract

The Philippines is a globally important area for biodiversity conservation, due to the high levels of species diversity and endemism in the islands. Much of this resulted from the interplay of multiple faunal origins with dispersal and isolation of colonists into the archipelago, following comparable zoogeographic patterns and centers of endemism. Most of our conservation priorities are now based on these faunal regions coupled with levels of threat and the assembly of threatened endemic species. Priority is centered only on distinct species, often disregarding similarly threatened races, only to be valued upon elevation as a species as with bleeding-hearts (Gallicolumba) and hornbills (Aceros, Penelopides). However, recent developments in taxonomic research facilitated the review of many taxa, leading to extensive splitting of polytypic forms. Many Philippine birds are polytypic and have well distributed subspecies around the archipelago, a majority of which are endemic as defined in the Colasisi (Loriculus philippensis) and Flameback (Chrysocolaptes lucidus). Overall, avian diversity and endemism is drastically higher when considering endemic races. Many o these isolated races are inherently restricted in degraded islands or montane habitats and consequently classified as threatened such as with scops-owls (Otus) and racquet-tails (Prioniturus). Therefore, there is a need to amend our current conservation priorities in the Philippines to address the issue of apparent multiple splits and the explosion of new threatened island endemic birds. Due to the enormity of subspecies, it would take a lifetime to review and validate splits, and considering the rapid decline of insular birds and their habitats, we need to address these conservation issues more urgently. In order to identify which taxa should be prioritized, we need to understand the phylogeny and distribution patterns of closely-related splits in both species and subspecies.

In this paper, a rarely used concept in animal systematics -- "Superspecies" (Mayr,1969) is applied to various endemic island birds to determine key biogeographic relations and potential splits. Analysis was directed on several polytypic species and known congeners to assemble constituent taxa that form a distinct Superspecies. Groups were identified within polytypic forms based on morphology, behavior and geographic isolation. Insular distribution of component semispecies are analyzed to show trends in both clumping and isolation, with implications to speciation, thus defining apparent taxonomic relations leading to splits. issues concerning semispecies are also discussed supporting the validity of elevating component subspecies. Analysis was also done to test levels of Allopatry and Sympatry among selected congeneric birds such as the brown-doves (Phapitreron), hornbills (Anthracoceros), malkohas (Phaenicophaeus) and tailorbirds (Orthotomus) to show validity of splits. Amongst the Superspecies, Prioniturus, Penelopides, and Gallicolumba were widely distributed and have undergone further speciation, but was less apparent for Loriculus having been retained as geographic isolates. In Gallicolumba and Penelopides, isolation is a mechanism for speciation and such polytypic taxa were grouped into 'species of convenience' thus partitioned based primarily on morphological difference. In Prioniturus and Otus, isolation and competition for ecological feeding niches, caused the separation further into lowland and montane forms.

Resulting plotted distribution of superspecies were noted for levels of threat (such as deforestation, restricted range and lack of protection), providing the basis for the formulation key hotspots in the Philippines. Many small islands within faunal regions are seriously deforested providing fewer habitats for their island-endemic species or subspecies. Distribution patterns of most of the component semispecies follow faunal regions (Heaney, 1986), thus validating priorities given for critical key endemic bird areas (Mallari et al., 2001) such as Greater Sulu and Greater Mindoro. Some birds were more isolated within faunal regions, like Basilan and Eastern Visayan islands (Samar, Leyte and Bohol) in Greater Mindanao, and Catanduanes and Polilo Islands in Greater Luzon. minor faunal regions like the Romblon group and Batanes-Babuyan group of islands were also significant sites. Among the superspecies, several component species were already threatened such as Gallicolumba keayi, G. menagei, G. keayi, Prioniturus luconensis, P. platanae, and Penelopides mindorensis. Other component subspecies were also notably threatened such as Penelopides manillae subnigra, P. affinis basilanicus, Chrysocolaptes lucidus grandis, Loriculus philippensis dohertyi, L. p. mindorensis, L. p. bournsi, Gallicolumba luzonica rubiventris, G. criniger barletti, Otus megalotis nigrorum, O. elegans calayensis, O. mantananensis romblonis and O. m. cuyuensis. Unfortunately, it may have been too late for several semispecies such as Loriculus philippensis chrysonotus, L. p. siquijorensis and Penelopides panini ticaensis. Consequently, safeguarding component semispecies including island races of polytypic birds magnifies the importance of protecting threatened island subspecies. Therefore, stressing the need for conservation action on all restricted insular birds, both species and subspecies.

Location

UPLB Main Library Special Collections Section (USCS)

College

College of Arts and Sciences (CAS)

Language

English

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