Christopher E. Filardi

Explosive Pleistocene diversification and hemispheric expansion of a “great speciator”

Factors that influence speciation rates among groups of organisms are integral to deciphering macroevolutionary processes; however, they remain poorly understood. Here, we use molecular phylogenetic data and divergence time estimates to reconstruct the pattern and tempo of speciation within a widespread and homogeneous bird family (white-eyes, Zosteropidae) that contains an archetypal “great speciator.” Our analyses show that the majority of this species-rich family constitutes a clade that arose within the last 2 million years, yielding a per-lineage diversification rate among the highest reported for vertebrates (1.95–2.63 species per million years). However, unlike most rapid radiations reported to date, this burst of diversification was not limited in geographic scope, but instead spanned the entire Old World tropics, parts of temperate Asia, and numerous Atlantic, Pacific, and Indian Ocean archipelagos. The tempo and geographic breadth of this rapid radiation defy any single diversification paradigm, but implicate a prominent role for lineage-specific life-history traits (such as rapid evolutionary shifts in dispersal ability) that enabled white-eyes to respond rapidly and persistently to the geographic drivers of diversification.

Single origin of a pan-Pacific bird group and upstream colonization of Australasia

Oceanic islands have long served as natural laboratories for understanding the diversification of life. In particular, the many thousands of islands spanning the tropical Pacific support an unparalleled array of terrestrial communities whose patterns of diversity contributed fundamental insights to the development of classical speciation and biogeographic theory. Much of this work is founded on an assumption derived from traditional taxonomic approaches, namely that faunas on these widely separated archipelagos stem from a simple one-way, downstream flow of colonists from continents to islands. Here we show, with the use of molecular phylogenetic data from one of the original bird families used to justify this assumption, that a diverse array of endemic island genera and species are the product of a single radiation that diversified across all major Pacific archipelagos in a non-stepping-stone fashion, and recently recolonized continental areas. The geographic scope and lineage-specific approach of this study reveal evolutionary patterns long obscured by traditional taxonomic surveys and indicate that widely dispersed archipelagos can be sources of biological diversity.

Plumage and song differences mediate species recognition between incipient flycatcher species of the Solomon Islands

Changes in mating signals among populations contribute to species formation. Often these signals involve a suite of display traits of different sensory modalities (“multimodal signals”); however, few studies have tested the consequences of multimodal signal divergence with most focusing on only a single divergent signal or suite of signals of the same sensory modality. Populations of the chestnut-bellied flycatcher Monarcha castaneiventris vary in song and plumage color across the Solomon Islands. Using taxidermic mount presentation and song playback experiments, we tested for the relative roles of divergent song and color in homotypic (“same type”) recognition between one pair of recently diverged sister taxa (the nominate chestnut-bellied M. c. castaneiventris and the white-capped M. c. richardsii forms). We found that both plumage and song type influenced the intensity of aggressive response by territory-owners, with plumage color playing a stronger role. These results indicate that differences in plumage and song are used in homotypic recognition, suggesting the importance of multimodal signal divergence in the evolution of premating reproductive isolation.

Difference in plumage color used in species recognition between incipient species is linked to a single amino acid substitution in the melanocortin-1 receptor.

Many studies demonstrate that differences in mating signals are used by incipient species in recognizing potential mates or sexual competitors (i.e., species recognition). Little is known, however, about the genetic changes responsible for these differences in mating signals. Populations of the Monarcha castaneiventris flycatcher vary in plumage color across the Solomon Islands, with a subspecies on Makira Island having chestnut bellies and blue‐black upper parts (Monarcha castaneiventris megarhynchus) and a subspecies on neighboring satellite islands being entirely blue‐black (melanic; Monarcha castaneiventris ugiensis). Here we show that a single nonsynonymous point mutation in the melanocortin‐1 receptor (MC1R) gene is present in all melanic birds from one island (Santa Ana) but absent in all chestnut‐bellied birds from Makira Island, implicating this mutation in causing melanism. Birds from a second satellite island (Ugi) do not show the same perfect association between this MC1R variant and plumage color, suggesting an alternative mechanism for melanism on this island. Finally, taxidermic mount presentation experiments in Makira (chestnut) and Santa Ana (melanic) suggest that the plumage difference mediates species recognition. Assuming that the signals used in species recognition are also used in mutual mate choice, our results indicate that a single amino acid substitution contributes to speciation.

Rapid diversification and secondary sympatry in Australo-Pacific kingfishers (Aves: Alcedinidae: Todiramphus)

Todiramphus chloris is the most widely distributed of the Pacifics ‘great speciators’. Its 50 subspecies constitute a species complex that is distributed over 16 000 km from the Red Sea to Polynesia. We present, to our knowledge, the first comprehensive molecular phylogeny of this enigmatic radiation of kingfishers. Ten Pacific Todiramphus species are embedded within the T. chloris complex, rendering it paraphyletic. Among these is a radiation of five species from the remote islands of Eastern Polynesian, as well as the widespread migratory taxon, Todiramphus sanctus. Our results offer strong support that Pacific Todiramphus, including T. chloris, underwent an extensive range expansion and diversification less than 1 Ma. Multiple instances of secondary sympatry have accumulated in this group, despite its recent origin, including on Australia and oceanic islands in Palau, Vanuatu and the Solomon Islands. Significant ecomorphological and behavioural differences exist between secondarily sympatric lineages, which suggest that pre-mating isolating mechanisms were achieved rapidly during diversification. We found evidence for complex biogeographic patterns, including a novel phylogeographic break in the eastern Solomon Islands that separates a Northern Melanesian clade from Polynesian taxa. In light of our results, we discuss systematic relationships of Todiramphus and propose an updated taxonomy. This paper contributes to our understanding of avian diversification and assembly on islands, and to the systematics of a classically polytypic species complex.

Grizzly bear monitoring by the Heiltsuk people as a crucible for First Nation conservation practice

Guided by deeply held cultural values, First Nations in Canada are rapidly regaining legal authority to manage natural resources. We present a research collaboration among academics, tribal government, provincial and federal government, resource managers, conservation practitioners, and community leaders supporting First Nation resource authority and stewardship. First, we present results from a molecular genetics study of grizzly bears inhabiting an important conservation area within the territory of the Heiltsuk First Nation in coastal British Columbia. Noninvasive hair sampling occurred between 2006 and 2009 in the Koeye watershed, a stronghold for grizzly bears, salmon, and Heiltsuk people. Molecular demographic analyses revealed a regionally significant population of bears, which congregate at the Koeye each salmon-spawning season. There was a minimum of 57 individual bears detected during the study period. Results also pointed to a larger than expected source geography for salmon-feeding bears in the study area (> 1000 km2), as well as early evidence of a declining trend in the bear population potentially explained by declining salmon numbers. Second, we demonstrate and discuss the power of integrating scientific research with a culturally appropriate research agenda developed by indigenous people. Guided explicitly by principles from Gvi’ilas or customary law, this research methodology is coupled with Heiltsuk culture, enabling results of applied conservation science to involve and resonate with tribal leadership in ways that have eluded previous scientific endeavors. In this context, we discuss the effectiveness of research partnerships that, from the outset, create both scientific programs and integrated communities of action that can implement change. We argue that indigenous resource management requires collaborative approaches like ours, in which science-based management is embedded within a socially and culturally appropriate context. We emerge not only with a set of guiding principles for resource management by the Heiltsuk, but a broadly applicable strategy that fosters intimacy with traditional lands and resources and provides a powerful engine for conservation.

The exceptional value of intact forest ecosystems

As the terrestrial human footprint continues to expand, the amount of native forest that is free from significant damaging human activities is in precipitous decline. There is emerging evidence that the remaining intact forest supports an exceptional confluence of globally significant environmental values relative to degraded forests, including imperilled biodiversity, carbon sequestration and storage, water provision, indigenous culture and the maintenance of human health. Here we argue that maintaining and, where possible, restoring the integrity of dwindling intact forests is an urgent priority for current global efforts to halt the ongoing biodiversity crisis, slow rapid climate change and achieve sustainability goals. Retaining the integrity of intact forest ecosystems should be a central component of proactive global and national environmental strategies, alongside current efforts aimed at halting deforestation and promoting reforestation.Forests that are free of significant human-induced degradation should be accorded urgent conservation priority, it is argued, owing to evidence that they hold particular value for biodiversity, carbon sequestration and storage, water provision, and the maintenance of indigenous cultures and human health.

Phylogeography of the Variable Dwarf-Kingfisher Ceyx lepidus (Aves: Alcedinidae) Inferred from Mitochondrial and Nuclear DNA Sequences

ABSTRACT. We reconstructed the phylogeographic relationships of the Variable Dwarf-Kingfisher (Ceyx lepidus) using DNA sequence data. Maximum likelihood and Bayesian analysis methods were used to reconstruct trees from a multilocus data set of all 15 named subspecies of the Ceyx lepidus species complex. The concatenated data-set length was 2,471 base pairs and included two mitochondrial genes and two noncoding nuclear introns. Support for the monophyly of C. lepidus was equivocal. We instead found support for a clade including all C. lepidus subspecies plus two endemic Philippine taxa: C. argentatus and C. cyanopectus. Relationships among subspecific taxa were not well resolved, and many nodes were collapsed into polytomies suggesting a rapid and widespread colonization. In situ diversification likely played a role in generating current diversity within four archipelagos: the Philippines, Malukus, Bismarcks, and Solomons. Some biogeographic patterns recovered for the Solomon Islands taxa match those seen in other bird species, such as the close relationship of taxa on Bougainville, Choiseul, and Isabel. By contrast, the sister relationship between populations on Guadalcanal and the New Georgia Group is novel. We discuss species limits and make taxonomic recommendations to treat all 15 subspecies of C. lepidus as species.

PATTERNS OF MOLECULAR AND MORPHOLOGICAL VARIATION IN SOME SOLOMON ISLAND LAND BIRDS

Abstract The Solomon Archipelago is the largest and most biologically complex archipelago in northern Melanesia. We collected tissues and voucher specimens from codistributed bird species found on five island groups that provided the first opportunity to apply molecular methods to this avifauna. Using the mitochondrial marker ND2, we constructed a series of intraspecific phylogenies for 23 ecologically and taxonomically diverse species (13 families from 5 orders). Intraspecific comparisons across islands revealed a broad range of genetic differentiation, from 0% in widespread dispersive species such as Eurystomus orientalis and Nectarinia jugularis, to as high as 4–8% in species such as Ceyx lepidus and Dicaeum aeneum. Fifteen of the 23 species had well-supported phylogeographic structure, and for many of these, endemic and otherwise, molecular phylogenetic relationships closely matched those delineated by morphology. However, degrees of genetic differentiation appeared to be inconsistent across taxonomic designations, and the monophyly of some endemic taxa was not well supported. The data reveal the limits of morphology in tracking complex evolutionary histories and suggest that taxonomic revision of some Solomon Islands birds is warranted. As the first molecular analyses of this avifauna, results presented here create a platform for further biogeographic and evolutionary studies of bird diversity in this influential region. Patrons de variation moléculaire et morphologique chez quelques oiseaux terrestres des îles Salomon

AVIFAUNA OF A LOWLAND FOREST SITE ON ISABEL, SOLOMON ISLANDS

Abstract We provide the first comprehensive description of a bird community from a lowland rainforest site on a major island in the Solomon Islands. During two dry season visits (July 1997, June 1998) to the lower Garanga River valley on the island of Isabel, we recorded 65 resident and 6 migrant species of birds. We document relative abundances, habitat preferences, and foraging guilds for the members of the bird community. The Garanga River site sustains all but 11 of the 76 species of landbirds known from Isabel. Of those 11 species, four are small-island or beach specialists, three are montane, and four are of unknown status. Habitat heterogeneity, maintained largely by river dynamics, is a major contributor to avian diversity at the site. The avifauna is dominated by nonpasserines, especially parrots, pigeons, kingfishers, and hawks. The flightless rail Nesoclopeus woodfordi, previously regarded as rare and threatened with extinction, was common. We recorded Ixobrychus flavicollis, Falco severus, and Eudynamys scolopacea for the first time on Isabel. We also documented occurrence in the lowlands of Micropsitta finschii, Collocalia spodiopygia, Coracina caledonica, and Pachycephala pectoralis, four species previously thought to be confined to upper elevations on Isabel. The depauperate understory avifauna of the Garanga River site may be anthropogenic and could belie what otherwise seems to be an intact avifauna.