Evolution of cave living in Hawaiian Schrankia (Lepidoptera: Noctuidae) with description of a remarkable new cave species

Although temperate cave‐adapted fauna may evolve as a result of climatic change, tropical cave dwellers probably colonize caves through adaptive shifts to exploit new resources. The founding populations may have traits that make colonization of underground spaces even more likely. To investigate the process of cave adaptation and the number of times that flightlessness has evolved in a group of reportedly flightless Hawaiian cave moths, we tested the flight ability of 54 Schrankia individuals from seven caves on two islands. Several caves on one island were sampled because separate caves could have been colonized by underground connections after flightlessness had already evolved. A phylogeny based on approximately 1500 bp of mtDNA and nDNA showed that Schrankia howarthi sp. nov. invaded caves on two islands, Maui and Hawaii. Cave‐adapted adults are not consistently flightless but instead are polymorphic for flight ability. Although the new species appears well suited to underground living, some individuals were found living above ground as well. These individuals, which are capable of flight, suggest that this normally cave‐limited species is able to colonize other, geographically separated caves via above‐ground dispersal. This is the first example of an apparently cave‐adapted species that occurs in caves on two separate Hawaiian islands. A revision of the other Hawaiian Schrankia is presented, revealing that Schrankia simplex, Schrankia oxygramma, Schrankia sarothrura, and Schrankia arrhecta are all junior synonyms of Schrankia altivolans. © 2009 The Linnean Society of London, Zoological Journal of the Linnean Society, 2009, 156 , 114–139.     

SEQUENTIAL RADIATIONS AND PATTERNS OF SPECIATION IN THE HAWAIIAN CRICKET GENUS LAUPALA INFERRED FROM DNA SEQUENCES

The tremendous diversity of endemic Hawaiian crickets is thought to have originated primarily through intraisland radiations, in contrast to an interisland mode of diversification in the native Hawaiian Drosophila. The Hawaiian cricket genus Laupala (family Gryllidae) is one of several native genera of flightless crickets found in rain-forest habitat across the Hawaiian archipelago. I examined the phylogenetic relationships among mitochondrial DNA (mtDNA) sequences sampled from 17 species of Laupala, including the 12S ribosomal RNA (rRNA), transfer RNA (RNA)^val and 16S rRNA regions. The distribution of mtDNA variants suggests that species within Laupala are endemic to single islands. The phylogenetic estimate produced from both maximum likelihood and maximum parsimony supports the hypothesis that speciation in Laupala occurred mainly within islands. The inferred biogeographical history suggests that diversification in Laupala began on Kauai, the oldest rain-forested Hawaiian island. Subsequently, colonization to younger islands in the archipelago resulted in a radiation of considerable phylogenetic diversity. Phylogenetic patterns in mtDNA are not congruent with prior systematic or taxonomic hypotheses. Hypotheses that may explain the conflict between the phylogenetic patterns of mtDNA variation and the species taxonomy are discussed.     

Seasonal surveillance confirms the range expansion of Aedes japonicus japonicus (Theobald) (Diptera: Culicidae) to the Hawaiian Islands of Oahu and Kauai

The Asian bush mosquito, Aedes japonicus japonicus (Theobald) was not known to occur in the Hawaii archipelago until it was identified on the island of Hawaii in 2003. This mosquito species remained undetected on the neighboring islands for 8?years before it was discovered at the Honolulu International Airport on Oahu in 2012. By 2015, four Ae. j. japonicus mosquitoes were collected in the western mountains of Oahu and one was collected in the central mountains of Kauai. The collection of this invasive mosquito species across the neighboring Hawaiian Islands of Oahu and Kauai indicated the need for increased seasonal surveillance on these islands. Following nearly four years of surveillance, Ae. j. japonicus was also confirmed to occur in the eastern mountains of Oahu and in the central mountainous region of Kauai. To expand the knowledge of the spread of invasive mosquitoes species further surveillance is necessary to identify all possible areas where populations of Ae. j. japonicus and other invasive mosquito species occur in Hawaiian archipelago.     

Long-term population trends of endangered Hawaiian waterbirds

We analyzed long-term winter survey data (1956–2007) for three endangered waterbirds endemic to the Hawaiian Islands, the Hawaiian moorhen (Gallinula chloropus sandvicensis), Hawaiian coot (Fulica alai), and Hawaiian stilt (Himantopus mexicanus knudseni). Time series were analyzed by species–island combinations using generalized additive models, with alternative models compared using Akaike information criterion (AIC). The best model included three smoothers, one for each species. Our analyses show that all three of the endangered Hawaiian waterbirds have increased in population size over the past three decades. The Hawaiian moorhen increase has been slower in more recent years than earlier in the survey period, but Hawaiian coot and stilt numbers still exhibit steep increases. The patterns of population size increase also varied by island, although this effect was less influential than that between species. In contrast to earlier studies, we found no evidence that rainfall affects counts of the target species. Significant population increases were found on islands where most wetland protection has occurred (Oahu, Kauai), while weak or no increases were found on islands with few wetlands or less protection (Hawaii, Maui). Increased protection and management, especially on Maui where potential is greatest, would likely result in continued population gains, increasing the potential for meeting population recovery goals.     

Phylogeography and ecology of an endemic radiation of Hawaiian aquatic case-bearing moths (Hyposmocoma: Cosmopterigidae)

The endemic moth genus Hyposmocoma (Lepidoptera: Cosmopterigidae) may be one of the most speciose and ecologically diverse genera in Hawaii. Among this diversity is the Hyposmocoma saccophora clade with previously unrecorded aquatic larvae. I present a molecular phylogeny based on 773 base pairs (bp) of the mitochondrial gene cytochrome c oxidase subunit I and 762 bp of the nuclear gene elongation factor 1-alpha. Topologies were constructed from data using maximum-parsimony, maximum-likelihood and Bayesian search criteria. Results strongly support the monophyly of the H. saccophora clade and the monophyly of the genus Hyposmocoma. The H. saccophora clade has single-island endemic species on Oahu, Molokai and West Maui. By contrast, there are three species endemic to Kauai, two being sympatric. The H. saccophora clade appears to follow the progression rule, with more basal species on older islands, including the most basal species on 11 Myr-old Necker Island, one of the Northwestern Hawaiian Islands. Aquatic behaviour either evolved recently in the species on the main Hawaiian Islands or was secondarily lost on the arid northwestern Necker Island. The phylogeny suggests that Hyposmocoma is older than any of the current main islands, which may, in part, explain Hyposmocoma's remarkable diversity.     

Insular black files (Diptera: Simuliidae) of North America: tests of colonization hypotheses

Aim To understand factors that facilitate insular colonization by black flies, we tested six hypotheses related to life‐history traits, phylogeny, symbiotes, island area, and distance from source areas. Location Four northern islands, all within 150 km of the North American mainland, were included in the study: Isle Royale, Magdalen Islands, Prince Edward Island, and Queen Charlotte Islands. Methods Immature black flies and their symbiotes were surveyed in streams on the Magdalen Islands, and the results combined with data from similar surveys on Isle Royale, Prince Edward Island, and the Queen Charlotte Islands. Black flies were analysed chromosomally to ensure that all sibling species were revealed. Tests of independence were used to examine the frequency of life‐history traits and generic representation of black flies on islands vs. source areas. Results A total of 13–20 species was found on each of the islands, but no species was unique to any of the islands. The simuliid faunas of the islands reflected the composition of their source areas in aspects of voltinism (univoltine vs. multivoltine), blood feeding (ornithophily vs. mammalophily), and phylogeny (genus Simulium vs. other genera). Five symbiotic species were found on the most distant island group, the Magdalen Islands, supporting the hypothesis that obligate symbiotes are effectively transported to near‐mainland islands. An inverse relationship existed between the number of species per island and distance from the source. The Queen Charlotte Islands did not conform to the species–area relationship. Main conclusions The lack of precinctive insular species and an absence of life‐history and phylogenetic characteristics related to the presence of black flies on these islands argue for gene flow and dispersal capabilities of black flies over open waters, possibly aided by winds. However, the high frequency of precinctive species on islands 500 km or more from the nearest mainland indicates that at some distance beyond 100 km, open water provides a significant barrier to colonization and gene exchange. An inverse relationship between number of species and distance from the source suggests that as long as suitable habitat is present, distance plays an important role in colonization. Failure of the Queen Charlotte Islands to conform to an area–richness trend suggests that not all resident species have been found.     

Convergent evolution of morphology and habitat use in the explosive Hawaiian fancy case caterpillar radiation

Species occurring in unconnected, but similar habitats and under similar selection pressures often display strikingly comparable morphology, behaviour and life history. On island archipelagos where colonizations and extinctions are common, it is often difficult to separate whether similar traits are a result of in situ diversification or independent colonization without a phylogeny. Here, we use one of Hawaii's most ecologically diverse and explosive endemic species radiations, the Hawaiian fancy case caterpillar genus Hyposmocoma, to test whether in situ diversification resulted in convergence. Specifically, we examine whether similar species utilizing similar microhabitats independently developed largely congruent larval case phenotypes in lineages that are in comparable, but isolated environments. Larvae of these moths are found on all Hawaiian Islands and are characterized by an extraordinary array of ecomorphs and larval case morphology. We focus on the ‘purse cases’, a group that is largely specialized for living within rotting wood. Purse cases were considered a monophyletic group, because morphological, behavioural and ecological traits appeared to be shared among all members. We constructed a phylogeny based on nuclear and mitochondrial DNA sequences from 38 Hyposmocoma species, including all 14 purse case species and 24 of non‐purse case congeners. Divergence time estimation suggests that purse case lineages evolved independently within dead wood and developed nearly identical case morphology twice: once on the distant Northwest Hawaiian Islands between 15.5 and 9 Ma and once on the younger main Hawaiian Islands around 3.0 Ma. Multiple ecomorphs are usually found on each island, and the ancestral ecomorph of Hyposmocoma appears to have lived on tree bark. Unlike most endemic Hawaiian radiations that follow a clear stepwise progression of colonization, purse case Hyposmocoma do not follow a pattern of colonization from older to younger island. We postulate that the diversity of microhabitats and selection from parasitism/predation from endemic predators may have shaped case architecture in this extraordinary endemic radiation of Hawaiian insects.     

Multiple origins of Hawaiian drosophilids: Phylogeography of Scaptomyza Hardy (Diptera: Drosophilidae)

Scaptomyza is a highly diversified genus in the family Drosophilidae, having undergone an explosive radiation, along with the Hawaiian‐endemic genus Idiomyia in the Hawaiian Islands: about 60% of 269 Scaptomyza species so far described are endemic to the Hawaiian Islands. Two hypotheses have been proposed for the origin and diversification of Hawaiian drosophilids. One is the “single Hawaiian origin” hypothesis: Scaptomyza and Idiomyia diverged from a single common ancestor that had once colonized the Hawaiian Islands, and then non‐Hawaiian Scaptomyza migrated back to continents. The other is the “multiple origins” hypothesis: Hawaiian Scaptomyza and Idiomyia derived from different ancestors that independently colonized the Hawaiian Islands. A key issue for testing these two hypotheses is to clarify the phylogenetic relationships between Hawaiian and non‐Hawaiian species in Scaptomyza. Toward this goal, we sampled additional non‐Hawaiian Scaptomyza species, particularly in the Old World, and determined the nucleotide sequences of four mitochondrial and seven nuclear genes for these species. Combining these sequence data with published data for 79 species, we reconstructed the phylogeny and estimated ancestral distributions and divergence times. In the resulting phylogenetic trees, non‐Hawaiian Scaptomyza species were interspersed in two Hawaiian clades. From a reconstruction of ancestral biogeography, we inferred that Idiomyia and Scaptomyza diverged outside the Hawaiian Islands and then independently colonized the Hawaiian Islands, twice in Scaptomyza, thus supporting the “multiple origins” hypothesis.     

Repeated range expansion and niche shift in a volcanic hotspot archipelago: Radiation of C4 Hawaiian Euphorbia subgenus Chamaesyce (Euphorbiaceae)

Woody perennial plants on islands have repeatedly evolved from herbaceous mainland ancestors. Although the majority of species in Euphorbia subgenus Chamaesyce section Anisophyllum (Euphorbiaceae) are small and herbaceous, a clade of 16 woody species diversified on the Hawaiian Islands. They are found in a broad range of habitats, including the only known C₄ plants adapted to wet forest understories. We investigate the history of island colonization and habitat shift in this group. We sampled 153 individuals in 15 of the 16 native species of Hawaiian Euphorbia on six major Hawaiian Islands, plus 11 New World close relatives, to elucidate the biogeographic movement of this lineage within the Hawaiian island chain. We used a concatenated chloroplast DNA data set of more than eight kilobases in aligned length and applied maximum likelihood and Bayesian inference for phylogenetic reconstruction. Age and phylogeographic patterns were co‐estimated using BEAST. In addition, we used nuclear ribosomal ITS and the low‐copy genes LEAFY and G3pdhC to investigate the reticulate relationships within this radiation. Hawaiian Euphorbia first arrived on Kaua`i or Ni`ihau ca. 5 million years ago and subsequently diverged into 16 named species with extensive reticulation. During this process Hawaiian Euphorbia dispersed from older to younger islands through open vegetation that is disturbance‐prone. Species that occur under closed vegetation evolved in situ from open vegetation of the same island and are only found on the two oldest islands of Kaua`i and O`ahu. The biogeographic history of Hawaiian Euphorbia supports a progression rule with within‐island shifts from open to closed vegetation.     

Microevolutionary patterns and processes of the Native Hawaiian colonizing fern Odontosoria chinensis (Lindsaeaceae)

Abstract.— The vascular‐plant flora of the Hawaiian Islands is characterized by one of the highest rates of species endemism in the world. Among flowering plants, approximately 89% of species are endemic, and among pteridophytes, about 76% are endemic. At the single‐island level, however, rates of species endemism vary dramatically between these two groups with 80% of angiosperms and only 6% of pteridophytes being single‐island endemics. Thus, in many groups of Hawaiian angiosperms, it is possible to link studies of phylogeny, evolution, and biogeographic history at the interspecific and interisland levels. In contrast, the low level of single‐island species endemism among Hawaiian pteridophytes makes similar interspecific and interisland studies nearly impossible. Higher levels of interisland gene flow may account for the different levels of single‐island endemism in Hawaiian pteridophytes relative to angiosperms. The primary question we addressed in the present study was: Can we infer microevolutionary patterns and processes among populations within widespread species of Hawaiian pteridophytes wherein gene flow is probably common? To address this broad question, we conducted a population genetic study of the native Hawaiian colonizing species Odontosoria chinensis. Data from allozyme analyses allowed us to infer: (1) significant genetic differentiation among populations from different islands; (2) historical patterns of dispersal between particular pairs of islands; (3) archipelago‐level patterns of dispersal and colonization; (4) founder effects among populations on the youngest island of Hawaii; and, (5) that this species primarily reproduces via outcrossing, but may possess a mixed‐mating system.