USE OF MACROINVERTEBRATES IN BIOASSESSMENT OF LAND USE AND WATER QUALITY IN NORTHERN MONGOLIA

Land-use practices in Mongolia lead to habitat degradation and consequently affect the structure and function of biological communities. There is no accepted bioassessment technique for determining the ecological consequences of habitat degradation on biological communities and water quality in Mongolia, such that a monitoring and management program suitable for Mongolia is sorely needed. Both a trait-based approach and the North American Rapid Bioassessment Protocol (RBP) metrics were tested with macroinvertebrates to determine the performance and applicability of these approaches for predicting general ecological responses of freshwater and terrestrial communities to habitat variation due to overgrazing and mining in northern Mongolian streams. Significant declines in functional diversity were observed by TBA with greater levels of land use intensity (more grazing and mining), and 13 of 16 traits (such as reproduction, life stages, resistant form, dissemination method, locomotion and substrate relation, feeding habit, food, saprobity, temperature, trophic level, current velocity, and substrate preferendum) varied significantly among different levels of land-use intensity. There were no significant differences observed among traits associated with an r/K reproductive strategy among the sites. In addition, complying with the RBP protocols, taxonomic richness and diversity and the number of taxa deemed intolerant to disturbance were significantly lower in sites with more grazing and mining than in more natural sites. However, despite the fact that mayflies are generally associated with low levels of disturbance, the abundance of mayflies (Ephemeroptera) and the percentage of taxon richness and abundance of mayflies was higher in sites with greater land-use intensity. Also, the RBP biotic index classification system for water quality was not well suited for use with Mongolian taxa. To determine the level of taxonomic resolution needed for accurate functional description, I compared functional diversity and trait responses from a coarse taxonomic level and from species-level resolution in one genus of macroinvertebrates (Simulium). Species-level resolution provided more information than genus-level resolution for some traits related to habitat association, but species-level resolution did not improve discrimination of land-use impacts substantially. Furthermore, I assessed land-use effects on terrestrial communities. Crane flies (Diptera: Tipuloidea) are a diverse group and vulnerable to habitat destruction because of their semi-terrestrial habit. Livestock grazing effects on crane fly diversity were tested among sites with different levels of grazing intensity. Species richness and diversity of crane flies were lower for moderately and highly grazed valleys than for the lightly grazed valleys. Soil moisture, plant biomass, and livestock number were the most significant predictors of variation in crane fly diversity across the grazing gradient. Overall, my study showed a strong relationship between functional and taxonomic structure of the macroinvertebrate community and habitat conditions. Generally, TBA and taxonomic approaches discriminated seminatural sites from sites with greater levels of land-use intensity. However, TBA provided a more direct explanation for macroinvertebrate responses to land-use and therefore may be more reliable for a future freshwater biomonitoring program in Mongolia. Species-level resolution may not be necessary for discriminating intensities of grazing and mining. Semiterrestrial crane fly community responses accurately reflected intensities of grazing in northern Mongolia. Among the results, there is a strong relationship between community structure and habitat condition. Habitat filtering determines variability of macroinvertebrate community observed among sites

Plant species composition and vegetation cover of Kherlen Toono Mountain, Mongolia

The Kherlen Toono Mountain Natural Reserve has a unique natural formation that makes its flora and vegetation cover unique. This study aimed to prepare a species inventory of flora and conduct make visual assessments of the vegetation cover of Kherlen Toono Mountain. A total of 202 species belonging to 115 genera, 46 families, and 4 phyla (Equisetophyta, Polypodiophyta, Pinophyta, and Magnoliophyta) were recorded. During this study, a species [Vincetoxicum lanceolatum (Grubov) Grubov] was newly recorded in the vegetation of the Dundad Khalkh district. An endemic species, 7 subendemic species (4.9%), and 10 rare species (3.9%) were recorded in the study area, which comprised 8.9% of the total species. These species recordings indicated the unique flora of the Kherlen Toono Mountain region. Forb–khargana and needle grass–forb communities of 10 different communities were commonly recorded in the study area

Chromosomal Translocations in Black Flies (Diptera: Simuliidae)-Facilitators of Adaptive Radiation?

A macrogenomic investigation of a Holarctic clade of black flies-the Simulium cholodkovskii lineage-provided a platform to explore the implications of a unique, synapomorphic whole-arm interchange in the evolution of black flies. Nearly 60 structural rearrangements were discovered in the polytene complement of the lineage, including 15 common to all 138 analyzed individuals, relative to the central sequence for the entire subgenus Simulium. Three species were represented, of which two Palearctic entities (Simulium cholodkovskii and S. decimatum) were sympatric; an absence of hybrids confirmed their reproductive isolation. A third (Nearctic) entity had nonhomologous sex chromosomes, relative to the other species, and is considered a separate species, for which the name Simulium nigricoxum is revalidated. A cytophylogeny is inferred and indicates that the two Palearctic taxa are sister species and these, in turn, are the sister group of the Nearctic species. The rise of the S. cholodkovskii lineage encompassed complex chromosomal and genomic restructuring phenomena associated with speciation in black flies, viz. expression of one and the same rearrangement as polymorphic, fixed, or sex linked in different species; taxon-specific differentiation of sex chromosomes; and reciprocal translocation of chromosome arms. The translocation is hypothesized to have occurred early in male spermatogonia, with the translocated chromosomal complement being transmitted to the X- and Y-bearing sperm during spermatogenesis, resulting in alternate disjunction of viable F1 translocation heterozygotes and the eventual formation of more viable and selectable F2 translocation homozygous progeny. Of 11 or 12 independently derived whole-arm interchanges known in the family Simuliidae, at least six are associated with subsequent speciation events, suggesting a facilitating role of translocations in adaptive radiations. The findings are discussed in the context of potential structural and functional interactions for future genomic research

Frequency of rearranged constituents for all chromosomal rearrangements in the <i>Simulium cholodkovskii</i> lineage, relative to the <i>Simulium</i> subgeneric standard.

<p>Frequency of rearranged constituents for all chromosomal rearrangements in the <i>Simulium cholodkovskii</i> lineage, relative to the <i>Simulium</i> subgeneric standard.</p

IIS arm of <i>Simulium cholodkovskii</i> (female larva), showing the typical sequence (<i>IIS-1</i>,4,<i>5</i>,<i>6</i>).

<p>Limits of polymorphic inversions IIS-7–IIS-9 and IIS-11 are indicated by brackets; <i>6</i>_<i>a</i> and <i>6</i>_<i>b</i> denote alternative breakpoints for <i>IIS-6</i>. The standard sequence for the subgenus <i>Simulium</i> can be obtained from the <i>IIS-1</i>,4,<i>5</i>,<i>6</i> sequence by alphabetically ordering the fragments indicated by small letters ‘a’ through ‘n’ that appear below the chromosome. Ordering the fragments above the chromosome from ‘a’ to ‘h’ produces the Y-chromosome sequence (<i>IIS-1</i>,<i>5</i>,<i>6</i>,10) of <i>S</i>. <i>nigricoxum</i>, i.e. IIS-10 is Y linked (dotted lines), whereas IIS-4 is X-linked (dashed lines) and, therefore, absent on the Y. Bu = bulge, C = centromere, Hb = location of heteroband 43Hb, RoB = ring of Balbiani, tr = trapezoidal.</p

IIIL arm of <i>Simulium decimatum</i>, showing continuity of transposed arms IS and IIIL and the <i>IIIL-2</i>,<i>15</i>,<i>23</i> sequence.

<p>The map represents a composite male (sections 98–100) and female larva, with sections 10–87 from the Thelon River and the remainder from the Tuul River. Polymorphic inversion IIIL-17, IIIL-19, and IIIL-25 (shared with <i>S</i>. <i>cholodkovskii</i>) are indicated by brackets. C = centromere, cs = cup and saucer marker, N.O. = nucleolar organizer.</p

IS arm of <i>Simulium cholodkovskii</i> (female larva), showing the <i>IS-17</i>,<i>18</i>,<i>19</i>,20,21 sequence.

<p>Fixed inversions <i>IS-17</i>,<i>18</i>,<i>19</i> are indicated with arrows below the chromosome, and predominant polymorphic inversions IS-20 and IS-21 with arrows above the chromosome; the basic <i>IS-17</i>,<i>18</i>,<i>19</i> sequence can be obtained from the <i>IS-17</i>,<i>18</i>,<i>19</i>,20,21 sequence by alphabetically ordering the fragments indicated by small letters ‘a’ through ‘h’. Limits of polymorphic inversions IS-22, IS-27, and IS-28 are indicated by brackets. C = centromere, em = end marker, gl = glazed, “3” = 3 marker;? = band unaccounted for but attributed to section 7.</p

Cytophylogeny of the <i>Simulium cholodkovskii</i> lineage, with terminals depicted by idiograms of each species.

<p>The outgroups (<i>S</i>. <i>erythrocephalum</i> and <i>S</i>. <i>vittatum</i>) are not shown on the cladogram. Rearrangements are shown in italics if fixed synapomorphies, in parentheses if polymorphic synapomorphies, and in square brackets if shared characters that could not be determined as plesiomorphic or synapomorphic. The homologues of each chromosome (I, II, III) are shown as tightly synapsed, and the arms are indicated as long (L) or short (S). Only diagnostic inversions (frequency > 0.10) for each species are shown on the idiograms. Fixed inversions are bracketed on the left. Polymorphic inversions are bracketed on the right as solid lines if autosomal, dashed if X-linked, and dotted if Y-linked. Landmarks are labeled on the idiogram for <i>S</i>. <i>cholodkovskii</i>: bl = blister with 2 heavy bands, Ce = centric region (with subscript indicating chromosome I, II, or III), em = end marker, Nk = neck, NO = nucleolar organizer, Pb = parabalbiani, RoB = ring of Balbiani.</p

IL arm of <i>Simulium nigricoxum</i> (female larva) from Canada, Thelon River, showing the <i>IL-1</i>,<i>17</i>,<i>18</i> sequence.

<p>The 3 fixed inversions are shown by a bracket (<i>IL-1</i>) and arrows (<i>IL-17</i>,<i>18</i>). The standard sequence for the subgenus <i>Simulium</i> can be obtained from the <i>IL-1</i>,<i>17</i>,<i>18</i> sequence by alphabetically ordering the fragments indicated by small letters ‘a’ through ‘l’. Limits of polymorphic inversions IL-19–IL-22 are indicated by brackets. C = centromere, Nk = neck.</p

Schematic derivation of the monocentric translocation homozygotes that define the <i>Simulium cholodkovskii</i> lineage.

<p>Diagnostic landmarks are given on idiograms for short (S) and long (L) arms of the three chromosomes (I, II, III). Both homologues of each chromosome are shown; bl = blister with 2 heavy bands, Ce = centric region containing putative centromere, em = end marker, Nk = neck, NO = nuclear organizer, Pb = parabalbiani, RoB = ring of Balbiani. Fixed inversions are italicized and bracketed on the left side of each chromosome; polymorphic inversions are in standard type and bracketed on the right side. A. Standard chromosomal complement, showing characteristic inversions of the <i>Simulium malyschevi</i> clade (<i>IL-1</i>, <i>IIL-1</i>, <i>IIL-2</i>, <i>IIIS-1</i>, and <i>IIIL-2</i>) from which the sequences of the <i>S</i>. <i>cholodkovskii</i> lineage are derived. From the ancestral intermediate through present-day members of the lineage (B–D), these inversions carry through as plesiomorphies, but are not shown in subsequent idiograms. B. Hypothetical intermediate of the <i>Simulium cholodkovskii</i> lineage, with characteristic fixed inversions established before the translocation event. Arrows 1 and 2 represent proximal and distal breaks, respectively, in the centric regions of chromosomes I and III. C. Derivation of a monocentric translocation heterozygote expressed as one of two possible scenarios: 1) As shown, chromosomal breaks occur in the proximal centric regions of chromosomes I and III (arrows 1 in Fig 10B) such that IS joins with CeIII plus IIIL and IL plus CeI joins with IIIS, giving rise to translocation heterozygote progeny (first generation). 2) (Not shown) chromosomal breaks occur in the distal centric regions of chromosomes I and III (arrows 2 in Fig 10B) such that IS plus CeI joins with IIIL and IL joins with CeIII plus IIIS. IIS is shown as the putative sex arm (X, Y). D. Monocentric translocation homozygote formed from an F1 mating. In our model, the first appearance of translocation homozygotes occurs in the F2 as a result of matings between F1 translocation males and females.</p