Ecology, biogeography and responses to habitat degradation of a highly diverse rainforest ant community and taxonomy of Afrotropical Pheidole Westwood (Hymenoptera, Formicidae) Dissertation zur Erlangung des Doktorgrades (Dr. rer. nat.) der Mathematisch-Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms-Universität Bonn vorgelegt von Georg Fischer aus Pirna Bonn, Oktober 2011 Angefertigt mit Genehmigung der Mathematisch- Naturwissenschaftlichen Fakultät der Rheinischen Friedrich-Wilhelms- Universität Bonn. Diese Arbeit wurde am Zoologischen Forschungsmuseum König in Bonn durchgeführt. Erstgutachter: Prof. Dr. J. Wolfgang Wägele Zweitgutachter: Prof. Dr. Wolfgang Böhme Kommissionsmitglied (fachnah): Prof. Dr. Dietmar Quandt Kommissionsmitglied (fachangrenzend): PD Dr. Torsten Wappler Erscheinungsjahr: 2012 2 Content Summary ......................................................................................................................................... 7 Zusammenfassung ........................................................................................................................ 12 Chapter 1: General Introduction ................................................................................................... 18 Biodiversity crisis .................................................................................................................. 18 Habitat destruction and degradation ................................................................................... 19 Species and functional diversity ........................................................................................... 21 Trophic chains and food web complexity ............................................................................. 23 Ant taxonomy ....................................................................................................................... 24 Kakamega Forest and study area ......................................................................................... 27 Outline .................................................................................................................................. 32 Chapter 2: The ants (Hymeoptera, Formicidae) of Kakamega Forest: Ecology and biogeography of a highly diverse mid-altitudinal rainforest fauna, with an updated species checklist.............. 35 Abstract ..................................................................................................................................... 35 Introduction .............................................................................................................................. 36 Material and Methods .............................................................................................................. 39 Ant sampling and examined material................................................................................... 39 Ecological and geographic distribution data ........................................................................ 40 Statistic analyses .................................................................................................................. 42 Results ....................................................................................................................................... 42 Faunal composition .............................................................................................................. 42 Ecological patterns ............................................................................................................... 45 Biogeography ........................................................................................................................ 49 Discussion ................................................................................................................................. 51 Ant Diversity ......................................................................................................................... 51 Ecological & biogeographical patterns ................................................................................. 52 Ants & Altitude ..................................................................................................................... 55 Conclusions ........................................................................................................................... 57 Appendix: Species checklist for the ants of Kakamega Forest and Western Kenya ............. 59 Chapter 3: Diversity, ecosystem functions and trophic ecology in a rainforest ant community (Hymenoptera, Formicidae) along a disturbance gradient in Western Kenya ............................. 78 Abstract ..................................................................................................................................... 78 Introduction .............................................................................................................................. 80 Material and Methods .............................................................................................................. 84 Research area & Study sites ................................................................................................. 84 3 Content Ant sampling and statistics ................................................................................................... 86 Stable isotopes and trophic chain length ............................................................................. 88 Ecosystem services scavenging ............................................................................................ 90 Functional Diversity .............................................................................................................. 90 Functional richness and diversity ......................................................................................... 93 Results ....................................................................................................................................... 95 Species richness and diversity .............................................................................................. 98 Trophic chain length and predators ..................................................................................... 99 Ecosystem Function Scavenging ......................................................................................... 101 Functional richness and diversity ....................................................................................... 103 Discussion ............................................................................................................................... 107 Species richness .................................................................................................................. 107 Functional diversity ............................................................................................................ 108 Trophic chain length ........................................................................................................... 110 Scavenging .......................................................................................................................... 111 Implications for conservation management ...................................................................... 113 Chapter 4: Taxonomy of the ant genus Pheidole Westwood (Hymenoptera, Formicidae) in the Afrotropical zoogeographic region: definition of species groups and systematic revision of the Pheidole pulchella group ............................................................................................................. 114 Abstract ................................................................................................................................... 114 Introduction ............................................................................................................................ 115 Material and Methods ............................................................................................................ 118 Measurements and indices ................................................................................................ 118 Indices ................................................................................................................................. 120 Taxonomy of Afrotropical Pheidole and preliminary species groups ................................. 121 P. excellens group: .......................................................................................................... 122 P. megacephala group: .................................................................................................. 123 P. nigeriensis group: ....................................................................................................... 123 P. aurivillii group: ........................................................................................................... 123 P. speculifera group: ...................................................................................................... 124 Definition of the P. pulchella group.................................................................................... 125 Diagnostic characters of minor workers ............................................................................ 125 Diagnostic characters of major workers ............................................................................. 126 General ecology of the P. pulchella group ......................................................................... 127