TY - JOUR
T1 - When rare species become endangered
T2 - Cryptic speciation in myrmecophilous hoverflies
AU - Schönrogge, Karsten
AU - Barr, Boyd
AU - Wardlaw, Judith C.
AU - Napper, Emma
AU - Gardner, Michael G.
AU - Breen, John
AU - Elmes, Graham W.
AU - Thomas, Jeremy A.
PY - 2002/3
Y1 - 2002/3
N2 - The myrmecophilous hoverfly, Microdon mutabilis, is listed as a 'Rare' or 'Nationally Notable Species' in UK Red Data Books. As an obligate social parasite, feeding only from ant colonies, its life-style satisfies theoretical conditions under which cryptic speciation is predicted to evolve; namely, strong selection for nonmorphological adaptations that enhance its exploitation of a local subspecies or populations of its host. Samples of larvae and pupae in Ireland, Scotland and England showed that M. mutabilis exploits a single and different host ant species on different sites across its range. In nine southern English colonies, 95.6% of infested nests were of Myrmica scabrinodis whereas in six Irish and two Scottish colonies 100% and 94.2%, respectively, of the infested nests were of Formica lemani, despite M. scabrinodis being common at all sites. Although the adults from 'scabrinodis' (and 'lemani) populations are cryptic, morphometric measurements of pupae showed consistent diagnostic characters that were sufficiently distinct for these ecotypes to be classed as separate species. We conclude that M. mutabilis is the 'lemani-type' and designate the 'scabrinodis-type' as a new species, Microdon myrmicae spec. nov. Thus, one of the listed threatened species of the British Isles becomes two species, each possessing about half the number of populations and occupying half the range of the original 'species'. Each also inhabits a different seral stage within grassland or heathland, and will require a different management regime if its declining populations are to be conserved. 'M. mutabills' is reported with other host ant species on the European continent. In the light of our results, these may prove to be additional cryptic species. We suggest that cryptic speciation is apt to evolve in species, such as myrmecophiles, endoparasites and koinobiont parasitoids, whose life-styles result in strong selection on their physiological or behavioural characters. The implications for Red Data Book classifications and for practical conservation are discussed.
AB - The myrmecophilous hoverfly, Microdon mutabilis, is listed as a 'Rare' or 'Nationally Notable Species' in UK Red Data Books. As an obligate social parasite, feeding only from ant colonies, its life-style satisfies theoretical conditions under which cryptic speciation is predicted to evolve; namely, strong selection for nonmorphological adaptations that enhance its exploitation of a local subspecies or populations of its host. Samples of larvae and pupae in Ireland, Scotland and England showed that M. mutabilis exploits a single and different host ant species on different sites across its range. In nine southern English colonies, 95.6% of infested nests were of Myrmica scabrinodis whereas in six Irish and two Scottish colonies 100% and 94.2%, respectively, of the infested nests were of Formica lemani, despite M. scabrinodis being common at all sites. Although the adults from 'scabrinodis' (and 'lemani) populations are cryptic, morphometric measurements of pupae showed consistent diagnostic characters that were sufficiently distinct for these ecotypes to be classed as separate species. We conclude that M. mutabilis is the 'lemani-type' and designate the 'scabrinodis-type' as a new species, Microdon myrmicae spec. nov. Thus, one of the listed threatened species of the British Isles becomes two species, each possessing about half the number of populations and occupying half the range of the original 'species'. Each also inhabits a different seral stage within grassland or heathland, and will require a different management regime if its declining populations are to be conserved. 'M. mutabills' is reported with other host ant species on the European continent. In the light of our results, these may prove to be additional cryptic species. We suggest that cryptic speciation is apt to evolve in species, such as myrmecophiles, endoparasites and koinobiont parasitoids, whose life-styles result in strong selection on their physiological or behavioural characters. The implications for Red Data Book classifications and for practical conservation are discussed.
KW - Cryptic species
KW - Formica
KW - Microdon mutabilis
KW - Microdon myrmicae
KW - Myrmecophily
KW - Myrmica
KW - Red Data Book
UR - http://www.scopus.com/inward/record.url?scp=0036520913&partnerID=8YFLogxK
U2 - 10.1046/j.1095-8312.2002.00019.x
DO - 10.1046/j.1095-8312.2002.00019.x
M3 - Article
AN - SCOPUS:0036520913
SN - 0024-4066
VL - 75
SP - 291
EP - 300
JO - Biological Journal of the Linnean Society
JF - Biological Journal of the Linnean Society
IS - 3
ER -