Genetic Differentiation, Structure, and a Transition Zone among Populations of the Pitcher Plant Moth Exyra semicrocea: Implications for Conservation

Abstract

Pitcher plant bogs, or carnivorous plant wetlands, have experienced extensive habitat loss and fragmentation throughout the southeastern United States Coastal Plain, resulting in an estimated reduction to <3% of their former range. This situation has lead to increased management attention of these habitats and their carnivorous plant species. However, conservation priorities focus primarily on the plants since little information currently exists on other community members, such as their endemic arthropod biota. Here, we investigated the population structure of one of these, the obligate pitcher plant moth Exyra semicrocea (Lepidoptera: Noctuidae), using mitochondrial cytochrome c oxidase subunit I (COI) gene sequences. Examination of 221 individuals from 11 populations across eight southeastern US states identified 51 unique haplotypes. These haplotypes belonged to one of two divergent (∼1.9–3.0%) lineages separated by the Mississippi alluvial plain. Populations of the West Gulf Coastal Plain exhibited significant genetic structure, contrasting with similarly distanced populations east of the Mississippi alluvial plain. In the eastern portion of the Coastal Plain, an apparent transition zone exists between two regionally distinct population groups, with a well-established genetic discontinuity for other organisms coinciding with this zone. The structure of E. semicrocea appears to have been influenced by patchy pitcher plant bog habitats in the West Gulf Coastal Plain as well as impacts of Pleistocene interglacials on the Apalachicola-Chattahoochee-Flint River Basin. These findings, along with potential extirpation of E. semicrocea at four visited, but isolated, sites highlight the need to consider other endemic or associated community members when managing and restoring pitcher plant bog habitats.

Do ecological communities disperse across biogeographic barriers as a unit?

“…We sample five arthropod species from this community: a moth, two flesh flies and two spiders (Table ). Inquilines include the moth, which spends its entire life cycle in the pitcher plant leaves (Jones, ; Stephens, Santos, & Folkerts, ), and the flesh flies, which are also tightly associated with the plant leaves (Dahlem & Naczi, ). Notably, both the moth and flies are poor flyers and dispersal limited (Folkerts, ; Krawchuk & Taylor, ; Rasic & Keyghobadi, ; Stephens & Folkerts, ).…”

Genetic implications of phylogeographical patterns in the conservation of the boreal wetland butterflyColias palaeno(Pieridae)

“…However, bogs have suffered from massive peat extractions during the last few centuries (Stoneman & Brooks, 1997;Howie, 2002). More recently, many bogs have been lost to agriculture, urbanization, and forestry (Wheeler & Proctor, 2000;Stephens et al, 2011). In Europe, the rate of this destruction has slowed down during the last few decades, although these habitats remain highly endangered, and newly-emerging threats include increased air and soil eutrophication (Spitzer & Danks, 2006), as well as climate change (Moore et al, 1998;Weltzin et al, 2003;Wu & Roulet, 2014).…”

Phylogeographic concordance factors quantify phylogeographic congruence among co-distributed species in theSarracenia alatapitcher plant system

“…A recent investigation into this moth utilizing mitochondrial DNA recovered a complete lack of haplotype sharing across the Mississippi River, and additional population structure east of the river (Stephens et al. ). In addition, multiple species of spiders act as capture interrupters, and opportunistically capture prey items that are attracted to the pitcher leaves.…”

“…But apart from E. semicrocea (Stephens et al. ), little is known regarding the phylogeographic structure of the associated arthropod species. Here, we generate DNA sequence data from six arthropod species to investigate the evolutionary history of the S. alata pitcher plant system.…”