Nest usurpation is an 'edge effect' for Carolina chickadees Poecile carolinensis

During 1995–1997, we monitored Carolina chickadee Poecile carolinensis nests in a fragmented forest landscape in northcentral Ohio, USA. Nest success was positively correlated with woodlot area and most nest loss was due to nest destruction by house wrens Troglodytes aedon . During 1998 and 1999, we conducted an experiment in both large (>6.8 ha) and small (<6.8 ha) woodlots in which we gave chickadees a choice of nesting on edges of woodlots (preferred wren habitat) or in the center of woodlots. We found no difference in nest success between large and small woodlots, but regardless of woodlot size, nest success was lower on edges than in the center. In the experiment, 100% of nest loss was due to nest destruction by house wrens. Given a choice, Carolina chickadees preferred to nest centrally more often than on edges. These results suggest that in fragmented landscapes where house wrens are common, nest destruction by house wrens is a major cause of nest failure in the Carolina chickadee. Such edge-dependent interspecific nest-site usurpation has not been previously recognized as a potentially important selective factor in nest site selection.     

A new species of Eimeria Schneider, 1885 (Apicomplexa: Eimeriidae) from the eastern gray squirrel,Sciurus carolinensis (Rodentia: Sciuridae: Sciurinae: Sciurini) from Oklahoma,USA

Systematic Parasitology - A new species of Eimeria Schneider, 1885 is described from an eastern gray squirrel (Sciurus carolinensis) from McCurtain County, Oklahoma, USA. Oöcysts of Eimeria...     

Frequency sensitivity in the auditory periphery of male and female black-capped chickadees (Poecile atricapillus)

The black-capped chickadee is a songbird that has been used extensively as a model of animal communication in field and laboratory settings. Although many studies have focused on the complex call and song systems of the black-capped chickadee, relatively fewer studies have focused on chickadee audition. However, we do know from behavioral and molecular work that chickadees (and auditory processing areas in their brains) discriminate between artificially generated tones, between conspecific and heterospecific vocalizations, and among different types of conspecific vocalizations. In this paper we investigate peripheral auditory processing of frequency in the black-capped chickadee and the potential influence of sex on frequency sensitivity using a technique called auditory evoked potentials. We found that male and female black-capped chickadees did not differ in any measure of frequency sensitivity. Both sexes had the greatest sensitivity to frequencies between 2 and 4 kHz. This range of frequencies is well represented in black-capped chickadee song, partially supporting the idea that sender and receiver coevolve. Finally, we suggest that the call and song system of North American parids make them an ideal taxonomic group for comparative work exploring the relationship between call systems and the evolution of auditory processing.     

Molecular phylogeny of short-tailed shrews, Blarina (Insectivora: Soricidae)

Phylogenetic relationships among the three described species of short-tailed shrews (genus Blarina) were inferred based on mitochondrial DNA sequences of 16S rRNA (506 bp) and cytochrome b (1137 bp) from 38 specimens representing B. brevicauda, B. hylophaga, and B. carolinensis, from across their range in North America. Phylogenetic analyses of both data sets combined followed tests showing lack of incongruence between these fragments. Analysis of substitution patterns indicated saturation of transitions at third codon positions in cytochrome b when Blarina sequences were compared to those of Sorex and Cryptotis, used as outgroups. Maximum-likelihood and weighted parsimony supported the monophyly of the genus and placed B. hylophaga as its basal branch, sister to B. brevicauda + B. carolinensis. Phylogeographic analysis revealed a significant partition between eastern and western populations of B. carolinensis and B. brevicauda, on either side of the Mississippi basin. These results are discussed in relation to cytogenetic, morphological, and fossil data.     

Seasonal variability in habitat structure may have shaped acoustic signals and repertoires in the black-capped and boreal chickadees

Many songbird species have evolved multiple vocalizations, or repertoires, that function to communicate various biological signals. More diverse repertoires may have evolved in response to the effects of seasonal variation in habitat structure on signal transmission. Such changes in habitat necessarily occur for migrating species, but they also occur for resident species that occupy deciduous forests. The black-capped chickadee (Poecile atricapillus) possesses a chick-a-dee call and a fee-bee song, but the closely related boreal chickadee (P. borealis) lacks a song. Consistent with the habitat variability hypothesis, the black-capped chickadee possesses a larger repertoire and primarily occupies deciduous forests, whereas the songless boreal chickadee occurs more often in coniferous forests. We explored the ecological basis of this hypothesis by recording audio playbacks of two species in two habitat types during two seasons. Specifically, we played both songs and calls of the black-capped chickadee and calls of the boreal chickadee in deciduous and coniferous habitats, prior to and after leaf-out. We measured attenuation and degradation in re-recorded vocalizations. For black-capped chickadees, the song was less degraded than the call in post-leaf, deciduous forests. The boreal chickadee call attenuated more quickly in all treatments, but maintained its acoustic structure better than both black-capped chickadee vocalizations in coniferous forests. Our results support the hypothesis that variable habitats provided a seasonal transmission benefit for both song and call in the black-capped chickadee, but that the transmission benefit of song is lost in the less variant coniferous forests, which may underlie the absence of a song in the boreal chickadee.     

A taxonomical investigation of the genus Corvomeyenia weltner (Spongillidae)

Summary The taxonomically problematic spongillid genus Corvomeyenia Weltner is analyzed. A north-south evolutionary series composed of Corvomeyenia everetti (Mills), Corvomeyenia carolinensis sp. nov., and Corvomeyenia australis Bonetto & Ezcurra de Drago can be demonstrated. C. carolinensis sp. nov. possesses spicular characteristics that indicate genetic variation from its congeners; in addition, environmental conditions in the type locality of C. carolinensis sp. nov. differ greatly from the optimal conditions for growth of C. everetti (Mills). A new method for phase contrast study of living sponge tissues and a variety of histological and histochemical techniques are used to taxonomically define C. carolinensis sp. nov.

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Zusammenfassung Die in taxonomischer Hinsicht problematische Spongilliden-gattung Corvomeyenia Weltner wird analysiert. Von Norden nach Süden lässt sich eine Entwicklungsreihe nachweisen, bestehend aus Corvomeyenia everetti (Mills), Corvomeyenia carolinensis sp. nov. sowie Corvomeyenia australis Bonetto & Ezcurra de Drago. Die Skelettnadeln von C. carolinensis sp. nov. weisen Merkmale auf, welche auf eine genetische Abweichung von seinen Gattungsverwandten hindeuten; überdies unterscheiden sich die Umweltsbedingungen an den Fundorten von C. carolinensis sp. nov. weitgehend von den optimalen Bedingungen für den Wuchs von C. everetti (Mills). Zur taxonomischen Bestimmung von C. carolinensis sp. nov. werden eine neue Methode der Phasenkontrastuntersuchung lebenden Schwam neue Methode der Phasenkontrastuntersuchung lebenden Schwammgewebes and verschiedene histologische und histochemische Methoden angewandt.

     

Effect of locomotor approach on feeding kinematics in the green anole (Anolis carolinensis)

Squamates are well-known models for studying to examine locomotor and feeding behaviors in tetrapods, but studies that integrate both behavioral activities remain scarce. Anolis lizards are a classical lineage to study the evolutionary relationships between locomotor behavior and complex structural features of the habitat. Here, we analyzed prey-capture behavior in one representative arboreal predator, Anolis carolinensis, to demonstrate the functional links between locomotor strategies and the kinematics of feeding. A. carolinensis uses two strategies to catch living insects on perches: Head-Up Capture and Jump Capture. In both cases, lizards use lingual prehension to capture the prey and the kinematic patterns of the trophic apparatus are not significantly influenced by the selected strategies. Therefore, to capture one prey type, movements of the trophic structures are highly fixed and A. carolinensis modulates the locomotor pattern to exploit the environment. Predation behavior in A. carolinensis integrates two different behavioral patterns: locomotor plasticity of prey-approach and biomechanical stereotypy of tongue prehension to successfully capture the prey.     

A test of the endogenous and exogenous selection hypotheses for the maintenance of a narrow avian hybrid zone

The contributions of genetic and environmental factors to differential reproductive success across hybrid zones have rarely been tested. Here, we report a manipulative experiment that simultaneously tested endogenous (genetic-based) and exogenous (environmental-based) selection within a hybrid zone. We transplanted mated pairs of two chickadee species (Poecile atricapilla and P. carolinensis) and their hybrids into isolated woodlots within their hybrid zone and monitored their reproductive success. Although clutch sizes were similar, based on an estimate of the genetic compatibility of a pair, hybrid pairs produced fewer nestlings and fledglings than did pairs of either parental species. According to a linear model generated from the data, a pure pair of either parental species would be expected to produce 1.91-2.48 times more fledglings per nesting attempt, respectively, than the average or least compatible pair in the experiment. Our result of decreased reproduction for hybrid pairs relative to parental species pairs within same environment (the hybrid zone in this experiment) support the endogenous selection hypothesis for maintenance of this hybrid zone. Because the experiment was conducted entirely within the hybrid zone (i.e., the same environment for parental and hybrid pairings), our data do not support the exogenous selection hypothesis as it predicts either all pairings doing poorly or the hybrid pairs more successful than the parental pairs.     

The occurrence of Corvomeyenia carolinensis (Harrison, 1971) (Porifera: Spongillidae) in Connecticut

Examination of spicules from a living sponge confirmed thepresenceof Corvomeyenia carolinensis in Mohawk Pond, LitchfieldCounty, Connecticut. Until recently this species had only beenreported from one locality in South Carolina. Based uponspiculeobservations in dated sediment samples this species appears tohaveexisted within Mohawk Pond throughout the past 100+years.     

Understanding avian responses to forest boundaries: a case study with chickadee winter flocks

Avian species diversity and territory location are often associated with sharp forest edges, or boundaries. However, our understanding of behaviours underlying avian distribution near forest boundaries, especially species with large home ranges, remains poor. In a two-year study, we measured chickadee flock movements in forests at 0–300 m from boundaries in an agricultural landscape near Edmonton, Alberta, Canada. Even though flocks foraged in all forested parts of the study area, only six of the 53 flocks studied foraged further from forest boundaries than expected if they had used their home range irrespectively of the distance to boundaries. We found no evidence that the association of chickadee flocks to forest boundaries resulted from vegetation changes near boundaries, or to changes in their foraging sites and foraging success near boundaries. However, chickadee flocks moved parallel to boundaries (<75 m away) twice as frequently as expected from random movement, thus suggesting that forest boundaries act as movement conduits. Even when birds do not apparently seek special features near forest boundaries, they may be closely associated with them, simply because their passive movements are constrained by habitat barriers defined by boundaries.     

chickadee encodes a profilin required for intercellular cytoplasm transport during Drosophila oogenesis.

The entire cytoplasmic contents of 15 highly polyploid nurse cells are transported rapidly to the oocyte near the end of Drosophila oogenesis. chickadee is one of a small group of genes whose mutant phenotype includes a disruption of this nurse cell cytoplasm transport. We have cloned the chickadee gene and found that cDNA clones encode a protein 40% identical to yeast and Acanthamoeba profilin. The nurse cells from chickadee egg chambers that lack ovary-specific profilin fail to synthesize cytoplasmic actin networks correctly. In addition, the nurse cell nuclei in chickadee egg chambers become displaced and often partially stretched through the channels leading into the oocyte, blocking the flow of cytoplasm. We suggest that the newly synthesized cytoplasmic actin networks are responsible for maintaining nuclear position in the nurse cells.     

When east meets west: population structure of a high-latitude resident species,the boreal chickadee (Poecile hudsonicus)

The population genetic structure of northern boreal species has been strongly influenced both by the Quaternary glaciations and the presence of contemporary barriers, such as mountain ranges and rivers. We used a combination of mitochondrial DNA (mtDNA), nuclear microsatellites and spatial distribution modelling to study the population genetic structure of the boreal chickadee (Poecile hudsonicus), a resident passerine, and to investigate whether historical or contemporary barriers have influenced this northern species. MtDNA data showed evidence of eastern and western groups, with secondary admixture occurring in central Canada. This suggests that the boreal chickadee probably persisted in multiple glacial refugia, one in Beringia and at least one in the east. Palaeo-distribution modelling identified suitable habitat in Beringia (Alaska), Atlantic Canada and the southern United States, and correspond to divergence dates of 60–96 kya. Pairwise F_ST values for both mtDNA and microsatellites were significant for all comparisons involving Newfoundland, though mtDNA data suggest a more recent separation. Furthermore, unlike mtDNA data, nuclear data support population connectivity among the continental populations, possibly due to male-biased dispersal. Although both are significant, the isolation-by-distance signal is much stronger for mtDNA (r²=0.51) than for microsatellites (r²=0.05), supporting the hypothesis of male-biased dispersal. The population structure of the boreal chickadee was influenced by isolation in multiple refugia and contemporary barriers. In addition to geographical distance, physical barriers such as the Strait of Belle Isle and northern mountains in Alaska are restricting gene flow, whereas the Rocky Mountains in the west are a porous barrier.     

A genetic analysis of grey squirrel (Sciurus carolinensis) populations in Ireland

Biological Invasions - The grey squirrel (Sciurus carolinensis) is an invasive rodent in Ireland that has had detrimental impacts on the native Irish red squirrel (S. vulgaris) as well as on...     

Eastern gray squirrel (Sciurus carolinensis) color morphs do not differ in aggressiveness

acta ethologica - Eastern gray squirrels (Sciurus carolinensis) exhibit a variety of color morphs, including black. In the USA and UK, a common folk belief is that black squirrels are more...     

Descriptions of the mature spermatozoa of the lizards Crotaphytus bicinctores, Gambelia wislizenii (Crotaphytidae), and Anolis carolinensis (Polychrotidae) (Reptilia, Squamata, Iguania)

The spermatozoa of Crotaphytus bicinctores and Gambelia wislizenii (Crotaphytidae), and Anolis carolinensis (Polychrotidae) exhibit the squamate autapomorphies of a single perforatorium extending anteriorly from the apical tip of the paracrystalline subacrosomal cone, the presence of an epinuclear electron-lucent region, and extension of the fibrous sheath into the midpiece. Crotaphytid sperm differ from those of polychrotids in several respects, including: the structure of the perforatorium, the size of the epinuclear electron-lucent region, aspects of the acrosome complex, the arrangement and structure of intermitochondrial dense bodies, and in the distance the fibrous sheath extends into the midpiece. The sperm of C. bicinctores, G. wislizenii, and A. carolinensis are most similar to those of the agamids and phrynosomatids examined to date. No spermatozoal autapomorphies for Crotaphytidae or Polychrotidae were found. The condition of having the intermitochondrial dense bodies arranged in regular incomplete rings is tentatively defined as a synapomorphy of Iguania (although modified in Chamaeleonidae). Spermatozoal ultrastructure offers no characters that justify the separation of Iguanidae (sensu lato) into several separate families.     

Eimeria carolinensis n. sp., a Coccidium from the White-Footed Mouse, Peromyscus leucopus (Rafinesque)

SYNOPSIS. Eimeria carolinensis n.sp. (Sporozoa) is described from oöcysts in the feces of the white-footed mouse, Peromyscus leucopus (Rafinesque) taken in the vicinity of Durham, North Carolina. The oöcysts are ellipsoidal to elongate ellipsoidal, 14–19.5 × 10–13 μ, mean of 17.6 × 11.3 μ. Micropyle absent. Oöcyst wall composed of 2 layers. A refractile granule present but no oöcyst residuum. Sporocysts ovoid almost filling the oöcyst. Small Stieda body present.     

Giant Amoebae from Colorado Identified by Transplantation Tolerance1

SYNOPSIS. Giant multinucleated amoebae, discovered in Colorado near Ft. Collins and tentatively identified as Pelomyxa carolinensis, were successfully cultured in a manner identical with that used for P. carolinensis. The ultrastructure of the Colorado amoebae, in comparison with that of other large amoebae, was like that of P. carolinensis, but different from those of Amoeba proteus, P. illinoisensis, and P. palustris. Protoplasmic grafts between the Colorado amoebae and P. carolinensis were then exchanged by microsurgery. These grafts were well tolerated, and the recipient amoebae reproduced at a rate comparable to that of non-grafted controls. Other Colorado amoebae received grafts from P. illinoisensis, but all recipients died without cell division a few days after microsurgery. These nutritional, cytologic and transplantation-tolerance data reveal that the amoebae from Colorado are P. carolinensis.     

Sympatry leads to reduced body condition in chickadees that occasionally hybridize

Both abiotic and biotic drivers influence species distributions. Abiotic drivers such as climate have received considerable attention, even though biotic drivers such as hybridization often interact with abiotic drivers. We sought to explore the (1) costs of co‐occurrence for ecologically similar species that hybridize and (2) associations between ecological factors and condition to understand how abiotic and biotic factors influence species distributions. For two closely related and ecologically similar songbirds, black‐capped and mountain chickadees, we characterized body condition, as a proxy for fitness, using a 1358‐individual range‐wide dataset. We compared body condition in sympatry and allopatry with several abiotic and biotic factors using species‐specific generalized linear mixed models. We generated genomic data for a subset of 217 individuals to determine the extent of hybridization‐driven admixture in our dataset. Within this data subset, we found that ~11% of the chickadees had hybrid ancestry, and all hybrid individuals had typical black‐capped chickadee plumage. In the full dataset, we found that birds of both species, independent of demographic and abiotic factors, had significantly lower body condition when occurring in sympatry than birds in allopatry. This could be driven by either the inclusion of cryptic, likely poor condition, hybrids in our full dataset, competitive interactions in sympatry, or range edge effects. We are currently unable to discriminate between these mechanisms. Our findings have implications for mountain chickadees in particular, which will encounter more black‐capped chickadees as black‐capped chickadee ranges shift upslope and could lead to local declines in mountain chickadee populations.     

A balance of capping protein and profilin functions is required to regulate actin polymerization in Drosophila bristle

Profilin is a well-characterized protein known to be important for regulating actin filament assembly. Relatively few studies have addressed how profilin interacts with other actin-binding proteins in vivo to regulate assembly of complex actin structures. To investigate the function of profilin in the context of a differentiating cell, we have studied an instructive genetic interaction between mutations in profilin (chickadee) and capping protein (cpb). Capping protein is the principal protein in cells that caps actin filament barbed ends. When its function is reduced in the Drosophila bristle, F-actin levels increase and the actin cytoskeleton becomes disorganized, causing abnormal bristle morphology. chickadee mutations suppress the abnormal bristle phenotype and associated abnormalities of the actin cytoskeleton seen in cpb mutants. Furthermore, overexpression of profilin in the bristle mimics many features of the cpb loss-of-function phenotype. The interaction between cpb and chickadee suggests that profilin promotes actin assembly in the bristle and that a balance between capping protein and profilin activities is important for the proper regulation of F-actin levels. Furthermore, this balance of activities affects the association of actin structures with the membrane, suggesting a link between actin filament dynamics and localization of actin structures within the cell.