Browsing by Author "Coulson, Robert N."
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- Africanization in the United States: Replacement of Feral European Honeybees (Apis mellifera L.) by an African Hybrid SwarmPublication . Pinto, M. Alice; Rubink, William L.; Patton, John C.; Coulson, Robert N.; Johnston, J. SpencerThe expansion of Africanized honeybees from South America to the southwestern United States in 50 years is considered one of the most spectacular biological invasions yet documented. In the American tropics, it has been shown that during their expansion Africanized honeybees have low levels of introgressed alleles from resident European populations. In the United States, it has been speculated, but not shown, that Africanized honeybees would hybridize extensively with European honeybees. Here we report a continuous 11-year study investigating temporal changes in the genetic structure of a feral population from the southern United States undergoing Africanization. Our microsatellite data showed that (1) the process of Africanization involved both maternal and paternal bidirectional gene flow between European and Africanized honeybees and (2) the panmitic European population was replaced by panmitic mixtures of A. m. scutellata and European genes within 5 years after Africanization. The post-Africanization gene pool (1998–2001) was composed of a diverse array of recombinant classes with a substantial European genetic contribution (mean 25–37%). Therefore, the resulting feral honeybee population of south Texas was best viewed as a hybrid swarm.
- Africanization of a feral honey bee (Apis mellifera) population in South Texas: does a decade make a difference?Publication . Rangel, Juliana; Giresi, Melissa; Pinto, M. Alice; Baum, Kristen A.; Rubink, William L.; Coulson, Robert N.; Johnston, J. SpencerThe arrival to the United States of the Africanized honey bee, a hybrid between European subspecies and the African subspecies Apis mellifera scutellata, is a remarkable model for the study of biological invasions. This immigration has created an opportunity to study the dynamics of secondary contact of honey bee subspecies from African and European lineages in a feral population in South Texas. An 11-year survey of this population (1991-2001) showed that mitochondrial haplotype frequencies changed drastically over time from a resident population of eastern and western European maternal ancestry, to a population dominated by the African haplotype. A subsequent study of the nuclear genome showed that the Africanization process included bidirectional gene flow between European and Africanized honey bees, giving rise to a new panmictic mixture of A. m. scutellata- and European-derived genes. In this study, we examined gene flow patterns in the same population 23 years after the first hybridization event occurred. We found 28 active colonies inhabiting 92 tree cavities surveyed in a 5.14 km(2) area, resulting in a colony density of 5.4 colonies/km(2). Of these 28 colonies, 25 were of A. m. scutellata maternal ancestry, and three were of western European maternal ancestry. No colonies of eastern European maternal ancestry were detected, although they were present in the earlier samples. Nuclear DNA revealed little change in the introgression of A. m. scutellata-derived genes into the population compared to previous surveys. Our results suggest this feral population remains an admixed swarm with continued low levels of European ancestry and a greater presence of African-derived mitochondrial genetic composition.
- Effects of the sustainable forestry Initiative on landscape function as measured by patterns of vertebrate habitatsPublication . Azevedo, João; Fisher, Richard F.; Wu, X. Ben; Messina, Michael G.; Coulson, Robert N.The Sustainable Forestry Initiative (SFI) adopted in 1995 by the American Forest and Paper Association is currently applied over 90% of industrial forests in the US. This program has potential effects on forest landscape structure and function, including biodiversity. Here we analyze the effects of SFI application on the abundance and spatial pattern of vertebrate habitats in a 6,000-ha forested watershed in East Texas. Simulations of landscape structure changes in the study area were conducted based on forest inventory data and SFI rules such as regeneration harvest areas limits of 49 ha for pine and 12 ha for hardwoods, streamside management zones 30 m or more wide, and a three-year green-up interval. The 266 species (83 herps, 132 birds, 51 mammals) of vertebrates potentially occurring in the study area were grouped into 12 clusters based upon their habitat requirements. One species per cluster was selected as the indicator species for the cluster. Habitat Suitability Index models were used to develop habitat suitability maps for the indicator species based on the landscape simulations. Habitat abundance and spatial characteristics for individual vertebrate species were evaluated at different points of time to assess the effects of the SFI on vertebrate habitats as compared to reference scenarios.
- Evidence of African honey bees mitotypes in the southern United States prior to Africanization as revealed by mtDNA sequence dataPublication . Pinto, M. Alice; Sheppard, Walter S.; Johnston, J. Spencer; Rubink, William L.; Coulson, Robert N.; Patton, John C.The standard protocol for assessing honey bees with a mitotype derived from an African origin is the amplification of a segment of cytochrome b and subsequent digestion of the amplified fragment with the restriction enzyme Bgl II. A previous survey of 451pre-Africanization honey bees from the southern U. S. revealed three bees with restriction pattern consistent with an African mitotype. To confirm these bees truly represented mitotypes of African origin we developed a new primer pair for amplification of cytochrome b, which utilizes internal sequencing primers to allow high quality direct sequence products. Using this system we amplified a mtDNA fragment of ~1,200 base-pairs (bp), taht included most of cytochrome b, serine (UCA) tRNA, and a small portion (s) of the ND-1 gene (s). Honey bees from ten morphometrically identified Apis mellifera subspecies (42 honey bee workers, each representing a different colony) from Old World and three honey bee workers (each representing a different colony) from the southern United States exhibiting an African phenotype as revealed by BglII restriction enzyme analysis were sequenced. The analysis showed that two of the three honey bees were of eastern European ancestry. These bees had lost the BglII cut site by a first position (C->A) transversion mutation. The third honey bee was found to have a sequence of African clade bees. This defining substitution for the African clade was found to be a third position (T->C) transiton mutation.
- Feral honey bees in pine forest landscapes of East TexasPublication . Coulson, Robert N.; Pinto, M. Alice; Tchakerian, Maria D.; Baum, Kristen A.; Rubink, William L.; Johnston, J. SpencerThe goal of this study was to investigate the diversity of feral honey bee races in pine forest landscapes of east Texas, subsequent to immigration of Africanized honey bees, Apis mellifera scutellata. The specific objectives were (i) to assess the immigration of A. m. scutellata into east Texas pine forest landscapes and (ii) to evaluate the suitability of the pine forest landscape to feral honey bees. This mesoscale landscape study was conducted on the Sam Houston National Forest in east Texas. Swarm traps and aerial pitfall traps were used to monitor feral honey bees. Spatial databases were used to evaluate suitability of the pine forest landscape for honey bees. Scoring mitochondrial DNA type (mitotypes), we found representatives of A. mellifera scutellata, eastern European, western European, and A. mellifera lamarckii races in pine forest landscapes of east Texas. The significant conclusions that follow from this evaluation are (i) honey bees are a ubiquitous component of the pine forest landscape in east Texas, (ii) mitotype diversity persists in the presence of significant immigration of A. m. scutellata, and (iii) A. m. scutellata, is an added element of the mitotype diversity in the landscape. The landscape structure in 1256 ha units surrounding 6 swarms of honey bees captured in swarm traps was examined. The metrics used to characterize the kind, number, size, shape, and configuration of elements forming the landscape, defined a heterogeneous environment for honey bees that included food and habitat resources needed for survival, growth, and reproduction.
- Feral honey bees in pine forest landscapes of East TexasPublication . Coulson, Robert N.; Pinto, M. Alice; Tchakerian, Maria D.; Baum, Kristen A.; Rubink, William L.; Johnston, J. SpencerIn 1990 the Africanized honey bee, a descendent of Apis mellifera scutellata, was identified in south Texas [Hunter, L.A., Jackman, J.A., Sugden,E.A., 1992.Detection records of Africanized honey bees inTexas during 1990, 1991 and 1992. Southwestern Entomol. 18, 79–89]. The potential impact of this immigrant on feral and managed colonies was the subject of considerable speculation. The goal of this study was to investigate the diversity of feral honey bee races in pine forest landscapes of east Texas, subsequent to immigration of A. m. scutellata. The specific objectives were (i) to assess the immigration of A. m. scutellata into east Texas pine forest landscapes and (ii) to evaluate the suitability of the pine forest landscape to feral honey bees. This mesoscale landscape study was conducted on the SamHouston National Forest in east Texas. Swarm traps and aerial pitfall traps were used to monitor feral honey bees. Spatial databases were used to evaluate suitability of the pine forest landscape for honey bees. Scoring mitochondrial DNA type (mitotypes), we found representatives of A. mellifera scutellata, eastern European, western European, and A. mellifera lamarckii races in pine forest landscapes of east Texas. The conclusions that follow from this aspect of the investigation are (i) honey bees are a ubiquitous component of the pine forest landscape in east Texas, (ii) mitotype diversity persists subsequent to the immigration of A. m. scutellata, and (iii) A. m. scutellata is an added element of the mitotype diversity in the landscape. To evaluate quantitatively the suitability of the pine forest to feral honey bees, we used a spatial database for the study area and FRAGSTATS. The landscape structure in 1256 ha units surrounding six swarms of honey bees captured in the swarm traps was examined. The metrics used to characterize the kind, number, size, shape, and configuration of elements forming the landscape, defined a heterogeneous environment for honey bees that included sufficient food and habitat resources needed for survival, growth, and reproduction. The conclusions that follow from this aspect of the investigation are (1) although classified as a pine forest, management practices and other human activities have altered the landscape and thereby created food and habitat resources suitable for honey bees, (2) the forestry practices associated specifically with road corridor maintenance, stream side corridor protection, RCW management, and Wilderness Area management introduce structural heterogeneity to the forest landscape which enriches the diversity and abundance of early successional flowering plants and provides cavity sites needed by honey bees, (3) ranching, farming, and urbanization within the study area also create these conditions, and (4) based on inferences from melissopalynology, honey bees provide pollination services for a broad representation of native and introduced flowering plant species of the pineywoods ecoregion.
- Functional heterogeneity of forest landscapes and the distribution and abundance of the red-cockaded woodpeckerPublication . Azevedo, João; Jack, Steven B.; Coulson, Robert N.; Wunneburger, Douglas F.Red-cockaded woodpecker (RCW, Picoides borealis) populations are greatly affected by the fragmentation of forest habitat through its effect on the dispersal of individuals between active clusters and other areas of the suitable habitat. In order to assess the suitability of a given landscape structure for the maintenance and expansion of RCW populations, land managers need an index that correlates with the bird's awareness of that structure. Rather than assuming that common landscape metrics provide the necessary information, we applied an index of functional heterogeneity to a GIS coverage for the western portion of the Sam Houston National Forest (SHNF) in east Texas, using two observation scales. In contrast to measured heterogeneity, functional heterogeneity incorporates the RCW response to forest structure. The GIS coverage included information on habitat suitability and RCW cluster distribution and size. The analyses indicated that the presence of cavity trees is the most important factor for RCW population maintenance and that fragmentation of the foraging habitat has much less impact. The analyses also indicated that many areas that are currently of high functional importance for the RCW are effectively isolated from one another. This second result has signi®cant implications for the dispersal of individuals between areas of high functionality and thus also the maintenance of the RCW in this forest. The functional heterogeneity analyses can also be used to examine the trade offs involved in managing the multiple wildlife species simultaneously and for examining the effects of various harvesting regimes through time.
- Functional heterogeneity of red-cockaded woodpecker habitat in the Sam Houston National Forest: insights for managementPublication . Azevedo, João; Jack, Steven B.; Coulson, Robert N.; Wunneburger, Douglas F.Red-cockaded woodpecker (RCW, Picoides borealis) populations are greatly affected by the fragmentation of forest habitat through the effect on dispersal between active clusters and the other suitable habitat. In order to assess the suitability of a given landscape structure for the maintenance and expansion of RCW populations, land managers need an index that correlates with the bird’s perception of that structure. Rather than assuming that the application of the most common landscape metrics will provide the necessary information, we applied three indices of functional heterogeneity (as opposed to measured heterogeneity) to a GIS coverage of the Raven District of the Sam Houston National Forest using two observable scales. The GIS coverage included information on habitat suitability and RCW cluster distribution and size. The analysis indicated that the presence of cavity trees is the most important factor for RCW population maintenance and that fragmentation of the foraging habitat has much less impact. The analysis also indicated that many areas currently of high functional importance for the RCW are effectively isolate from on another. This second result has significant implications for dispersal of individuals between areas of high functionality and this also the maintenance of RCW in this forest.
- Honey bees (Hymenoptera: Apidae) of african origin exist in non-africanized areas of the Southern United States: evidence from mitochondrial DNAPublication . Pinto, M. Alice; Sheppard, Walter S.; Johnston, J. Spencer; Rubink, William L.; Coulson, Robert N.; Schiff, Nathan M.; Kandemir, Irfan; Patton, John C.Descendents of Apis mellifera scutellata Lepeletier (Hymenoptera: Apidae) (the Africanized honey bee) arrived in the United States in 1990. Whether this was the Þrst introduction is uncertain. A survey of feral honey bees from non-Africanized areas of the southern United States revealed three colonies (from Georgia, Texas, and New Mexico) with a diagnostic African mitochondrial DNA cytochrome b/BglII fragment pattern. To assess maternal origin of these colonies, we developed a primer pair for ampliÞcation of a cytochrome b fragment and sequenced using internal sequencing primers. Samples of the three reported honey bee colonies plus another 42 representing the 10 subspecies known to have been introduced in the United States were sequenced. Of the three colonies, the colonies from Texas and New Mexico matched subspecies of European maternal ancestry, whereas the colony from Georgia was of African ancestry. Contrary to expectations, the mitotype of the latter colony was more similar to that exhibited by sub-Saharan A. m. scutellata than to the mitotypes common in north African A. m. intermissa Maa or Portuguese and Spanish A. m. iberiensis Engel. This Þnding was consistent with anecdotal evidence that A. m. scutellata has been sporadically introduced into the United States before the arrival of the Africanized honey bee from South America.
- Identification of africanized honey bee (Hymenoptera: apidae) mitochondrial DNA: validation of a rapid polymerase chain reaction-based assayPublication . Pinto, M. Alice; Johnston, J. Spencer; Rubink, William L.; Coulson, Robert N.; Patton, John C.; Sheppard, Walter S.Polymerase chain reaction (PCR)-ampliÞed mitochondrialDNA(mtDNA)assays have been used in studies of the Africanization process in neotropical feral and managed honey bee populations. The approach has been adopted, in conjunction with morphometric analysis, to identify Africanized bees for regulatory purposes in the United States such as in California. In this study, 211 Old World colonies, representing all known introduced subspecies in the United States, and 451 colonies from non-Africanized areas of the southern United States were screened to validate a rapid PCR-based assay for identiÞcation of Africanized honey bee mtDNA. This PCR-based assay requires a single enzyme digestion (BglII) of a single PCR-ampliÞed segment of the cytochrome b gene. The BglII polymorphism discriminates the mitochondrial haplotype (mitotype) of Apis mellifera scutellata L. (ancestor of Africanized bees) from that of A. m. mellifera, A. m. caucasia, A. m. ligustica, A. m. carnica, A. m. lamarcki, A. m. cypria, A. m. syriaca, and some A. m. iberiensis, but not from that of A. m. intermissa and some A. m. iberiensis. Nonetheless, given the very low frequency ( 1%) of African non-A. m. scutellata mitotype present before arrival of Africanized bees in the United States, cytochrome b/BglII assay can be used to identify maternally Africanized bees with a high degree of reliability.